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Hail Hydro!
- Thread starter PetFlora
- Start date
In preparation for harvesting the plants on the left under the TL D 200 (see previous pics), which were fed from one rez, I dumped the nutes and flushed for 2 days
Removed them from tent at lights out yesterday. Trimmed leafs this morning and put in the dark. Still not convinced dark period does anything, but, I am in no hurry, so...
I will give them sips of water twice a day for a couple days, then harvest.
What nuggz are there are very fat and tight. The plant on the left is 9"+ tall by 5" near the bottom
View attachment 349023 View attachment 349024
Removed them from tent at lights out yesterday. Trimmed leafs this morning and put in the dark. Still not convinced dark period does anything, but, I am in no hurry, so...
I will give them sips of water twice a day for a couple days, then harvest.
What nuggz are there are very fat and tight. The plant on the left is 9"+ tall by 5" near the bottom
View attachment 349023 View attachment 349024
The plant remaining under the TL D200 has really cranked the trichs. It's within a few days of coming down
View attachment 349183 View attachment 349184 View attachment 349185
I wasn't seeing any reason to continue with the dark period so I harvested 2 today. The large cola weighs 62gms!
View attachment 349186 View attachment 349187
View attachment 349183 View attachment 349184 View attachment 349185
I wasn't seeing any reason to continue with the dark period so I harvested 2 today. The large cola weighs 62gms!
View attachment 349186 View attachment 349187
The large cola plant that I harvested 3 days ago weighed 62gms trimmed. The whole plant is solid super tight bud. Doesn't squeeze under normal pressure. Be interesting to see dry weight
T5 ReVeg (now under 4 TL NW LED tubes)
After replacing nutes yesterday morning I checked the roots and was shocked how few there are
Somehow, the plant (in the rear/left in many prior pics) has almost no roots. I would need a macro lens to show them
The Mystery Seed Plant has just a few, so I am surprised to see all the new leaf growth
View attachment 349373 View attachment 349374
Also a shot of plant under the TL D200. I'm a believer, even though it is designed to supplement green house natural light, it did a fine job in a 7ft high tent
Now within days of harvest. Buds (especially the plant I harvested a few days ago) look as good as any I have harvested under other LED or HOT5 lamps
View attachment 349375
T5 ReVeg (now under 4 TL NW LED tubes)
After replacing nutes yesterday morning I checked the roots and was shocked how few there are
Somehow, the plant (in the rear/left in many prior pics) has almost no roots. I would need a macro lens to show them
The Mystery Seed Plant has just a few, so I am surprised to see all the new leaf growth
View attachment 349373 View attachment 349374
Also a shot of plant under the TL D200. I'm a believer, even though it is designed to supplement green house natural light, it did a fine job in a 7ft high tent
Now within days of harvest. Buds (especially the plant I harvested a few days ago) look as good as any I have harvested under other LED or HOT5 lamps
View attachment 349375
Turned the Light off today
This is a Mystery Seed that is either el Nino, Jack Herer or White Widow
She was abused by too much Gibberlic Acid as a seed. It's testament to how much abuse cannabis can take and still survive. They are, after all, weeds
She has a sweet pine scent
Anybody recognize her?
I'm leaning towards Jack Herer
View attachment 349673 View attachment 349674 View attachment 349675
This is a Mystery Seed that is either el Nino, Jack Herer or White Widow
She was abused by too much Gibberlic Acid as a seed. It's testament to how much abuse cannabis can take and still survive. They are, after all, weeds
She has a sweet pine scent
Anybody recognize her?
I'm leaning towards Jack Herer
View attachment 349673 View attachment 349674 View attachment 349675
Though the battle never materialized, I harvested and trimmed the Mystery Plant under the TL D200 this morning.
After going through a horrific childhood (gibberlic acid soaked seeds) she still blessed me with 104 gms trimmed and wet with main stem, so ~ an ounce when dried, which at ~ $15/gm is half the cost of the light, plus I grew another 2 plants under her (19gms dry).
Damned good value
My best guess is she’s a Jack Herer, which would be awesome, as it would were she White Widow or el Nino
I think I‘ve proven that the D 200 is a fine choice for growing cannabis in a typical indoor growers personal use space, even though it was designed specifically for supplemental lighting in greenhouses.
Indoor tent growers need to be made aware that it weighs a lot more than other similar watt options, and that the tent should be 7’+ high, due to the tall fixture
In spite of the D200 being ~ twice the upfront cost of the Amare SE 230/250, it’s Remote Phosphor technology is said to double the much over exaggerated 50K hours of most led lamps
View attachment 349910 View attachment 349911 View attachment 349912
After going through a horrific childhood (gibberlic acid soaked seeds) she still blessed me with 104 gms trimmed and wet with main stem, so ~ an ounce when dried, which at ~ $15/gm is half the cost of the light, plus I grew another 2 plants under her (19gms dry).
Damned good value
My best guess is she’s a Jack Herer, which would be awesome, as it would were she White Widow or el Nino
I think I‘ve proven that the D 200 is a fine choice for growing cannabis in a typical indoor growers personal use space, even though it was designed specifically for supplemental lighting in greenhouses.
Indoor tent growers need to be made aware that it weighs a lot more than other similar watt options, and that the tent should be 7’+ high, due to the tall fixture
In spite of the D200 being ~ twice the upfront cost of the Amare SE 230/250, it’s Remote Phosphor technology is said to double the much over exaggerated 50K hours of most led lamps
View attachment 349910 View attachment 349911 View attachment 349912
Sigh... none of the GWS seeds cracked from the 18th. [FONT=Arial, Helvetica, sans-serif]This was anticipated, but I had to try. [/FONT]
[FONT=Arial, Helvetica, sans-serif] [/FONT][FONT=Arial, Helvetica, sans-serif]
4 days ago I dropped 6 donated seeds that are a great cross, but I haven't located what they are. So far, only one has cracked: it already has a 1.5" tap root. [/FONT]
I just dropped 5 WW x Bubblegum F2 that are ~ 3 years old. Always in my fridge crisper area
__________________
[FONT=Arial, Helvetica, sans-serif] [/FONT][FONT=Arial, Helvetica, sans-serif]
4 days ago I dropped 6 donated seeds that are a great cross, but I haven't located what they are. So far, only one has cracked: it already has a 1.5" tap root. [/FONT]
I just dropped 5 WW x Bubblegum F2 that are ~ 3 years old. Always in my fridge crisper area
__________________
While reading a question about whether O2 injected into a rez would be beneficial, I responded as follows... When air pumps are on 24/7, they constantly pull O2 from the air in the room, but you got me thinking about germinating old or stubborn seeds: I just added a few drops of food grade H2O2 to the water the seeds are soaking in
Stay tuned
Stay tuned
The Importance of H and RH
The Importance of H and RH
I freely admit that I have not made an effort to dial this most important parameter in. I have been aware of it but never got around to getting a humidifier Shame on me! Will take care of this ASAP
Copied from another grow site
Michael Christian, the president of American Hydroponics since 1984, is a hydroponic system designer and consultant to commercial growers worldwide.
Humidity
The two ways of explaining humidity are relative humidity (RH) and vapor pressure deficit (VPD). Most people are familiar with RH and use hygrometers so, for the purposes of this article, I will use RH.
In my experience, this is the one variable that most growers need to be more aware of. The dance between temp/humidity directly affects transpiration rates as poor transpiration opens the plant organism to disease and mineral deficiencies.
RH is the amount of water vapor present in the air expressed as a % of the amount needed for saturation at the same temperature. Here’s what that means: if the humidity is too high, e.g. 95% at 75°F, plants cannot transpire or evaporate enough water to pull minerals up the vascular system even with stomata wide open. This usually results in calcium (Ca) deficiency (remember, Ca is a non-mobile element and must be constantly supplied to growing tips) and plant stress, which increases their vulnerability to fungal intrusion.
If humidity is too low, 50% at 75°F, stomata will open in an attempt to evaporate water because of the low pressure around the leaf, but then close up to conserve cell pressure in the leaf. Plants stress as they cannot take in CO2 with closed stomata and growth stops as the plant is just trying to survive without going into wilt (i.e. loss of leaf turgidity from which it’s difficult to recover). Again the plant is vulnerable to disease and insects. These two extremes points will create a high probability of crop loss.
As a rule, at 75°F (24°C), if RH is below 60% you must add moisture to get to 75% (which is ideal), but stay below 85% to avoid stress and disease. At 85°F (29°C), if RH is below 70% you must add moisture to get to 80% (which is ideal), but stay below 90% to avoid stress and disease. As temperature rises, air holds less moisture. Steer your plants within these parameters for optimum plant performance.
When RH is too low, use a fogger or humidifier coupled with outside air exchanges. When outside air is too warm and dry, you will have to use some form of air conditioner (if that is the only way) to drop the temperature to increase the moisture-holding capacity of the air.
When RH is too high, raise temperature to reduce moisture saturation of air coupled with outside air exchanges. If outside air has too high of an RH, you will need a dehumidifier to pull water out of the air.
Transpiration is king. Monitoring transpiration rates and keeping them optimum with temp/RH manipulation is crucial. If you are outside of the temp/RH safe zones and don’t use some mechanical method of bringing them under control, you will always be fighting the results of that variable being unchecked. This is where high quality environmental controllers come in handy
You can buy the most expensive nutrients, goodies and gadgets available to grow your crop, but if your plants are unable to transpire and you don’t know that, you had best learn quickly or get a day job
The Importance of H and RH
I freely admit that I have not made an effort to dial this most important parameter in. I have been aware of it but never got around to getting a humidifier Shame on me! Will take care of this ASAP
Copied from another grow site
Michael Christian, the president of American Hydroponics since 1984, is a hydroponic system designer and consultant to commercial growers worldwide.
Humidity
The two ways of explaining humidity are relative humidity (RH) and vapor pressure deficit (VPD). Most people are familiar with RH and use hygrometers so, for the purposes of this article, I will use RH.
In my experience, this is the one variable that most growers need to be more aware of. The dance between temp/humidity directly affects transpiration rates as poor transpiration opens the plant organism to disease and mineral deficiencies.
RH is the amount of water vapor present in the air expressed as a % of the amount needed for saturation at the same temperature. Here’s what that means: if the humidity is too high, e.g. 95% at 75°F, plants cannot transpire or evaporate enough water to pull minerals up the vascular system even with stomata wide open. This usually results in calcium (Ca) deficiency (remember, Ca is a non-mobile element and must be constantly supplied to growing tips) and plant stress, which increases their vulnerability to fungal intrusion.
If humidity is too low, 50% at 75°F, stomata will open in an attempt to evaporate water because of the low pressure around the leaf, but then close up to conserve cell pressure in the leaf. Plants stress as they cannot take in CO2 with closed stomata and growth stops as the plant is just trying to survive without going into wilt (i.e. loss of leaf turgidity from which it’s difficult to recover). Again the plant is vulnerable to disease and insects. These two extremes points will create a high probability of crop loss.
As a rule, at 75°F (24°C), if RH is below 60% you must add moisture to get to 75% (which is ideal), but stay below 85% to avoid stress and disease. At 85°F (29°C), if RH is below 70% you must add moisture to get to 80% (which is ideal), but stay below 90% to avoid stress and disease. As temperature rises, air holds less moisture. Steer your plants within these parameters for optimum plant performance.
When RH is too low, use a fogger or humidifier coupled with outside air exchanges. When outside air is too warm and dry, you will have to use some form of air conditioner (if that is the only way) to drop the temperature to increase the moisture-holding capacity of the air.
When RH is too high, raise temperature to reduce moisture saturation of air coupled with outside air exchanges. If outside air has too high of an RH, you will need a dehumidifier to pull water out of the air.
Transpiration is king. Monitoring transpiration rates and keeping them optimum with temp/RH manipulation is crucial. If you are outside of the temp/RH safe zones and don’t use some mechanical method of bringing them under control, you will always be fighting the results of that variable being unchecked. This is where high quality environmental controllers come in handy
You can buy the most expensive nutrients, goodies and gadgets available to grow your crop, but if your plants are unable to transpire and you don’t know that, you had best learn quickly or get a day job
2 Things, Well 3
2 Things, Well 3
1. I bought a 1.2G Vicks Humidifier. Running a clean cycle now and checking for how long a 1/2g takes to vaporize
2. pH: I bought a Cole Parmer pH Testr for $10 on Amazon. Hope it lasts longer than my uber expensive Hannas that don't last.
Previously, I was using pH drops, but it's too difficult to discern with 0.5- 1.0 differences
Where I thought I was ~ 5.8, it was at 6.2 no bueno for hydro vegging
3. Root development is virtually non existent on the Mystery Seed reveg, but it's developing a fair amount of new leafs. Oddly the other reveg has no new leaf development, BUT, it has new roots
Here's a snap shot to see how much the humidifier and more accurate pH contribute
View attachment 351077 View attachment 351078 View attachment 351079
2 Things, Well 3
1. I bought a 1.2G Vicks Humidifier. Running a clean cycle now and checking for how long a 1/2g takes to vaporize
2. pH: I bought a Cole Parmer pH Testr for $10 on Amazon. Hope it lasts longer than my uber expensive Hannas that don't last.
Previously, I was using pH drops, but it's too difficult to discern with 0.5- 1.0 differences
Where I thought I was ~ 5.8, it was at 6.2 no bueno for hydro vegging
3. Root development is virtually non existent on the Mystery Seed reveg, but it's developing a fair amount of new leafs. Oddly the other reveg has no new leaf development, BUT, it has new roots
Here's a snap shot to see how much the humidifier and more accurate pH contribute
View attachment 351077 View attachment 351078 View attachment 351079
More good news, another seed cracked, and one more looks ready.
Seems to be evidence that the H2O2 drops are working
On the reveg front
While the Vicks is working great now ~ 70% RH, the 1.2g capacity is being used up pretty quickly. Looks like I will need to refill daily- a small price for improved growth.
Lots of new leaf development on the front plant, but the one in the back seems to have taken a turn for the worse. WTF?
Pics tomorrow
Seems to be evidence that the H2O2 drops are working
On the reveg front
While the Vicks is working great now ~ 70% RH, the 1.2g capacity is being used up pretty quickly. Looks like I will need to refill daily- a small price for improved growth.
Lots of new leaf development on the front plant, but the one in the back seems to have taken a turn for the worse. WTF?
Pics tomorrow
[FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif]Seed + H2O2 update: l[/FONT][/FONT][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif]ooks like 2 more are about to crack
added 2 more drops
[/FONT][/FONT][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif]
Reveg Tent
[/FONT][/FONT][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif]I decided to turn the humidifier off over night, thinking without light (the 4 TLs create very little heat) + cool morning temp 53*s, that I just might be wasting water and electricity. RH was 54%
Tent temps now 65*. After running the humidifier for 5 minutes, RH quickly rose to 75%, which may be too high for the ambient temperature, as ideal RH range is ~ 75%, but that's when temp is between 75-85*, so it's likely a sliding scale. Dunno, but will investigate.
Seems like 5/5 o/o keeps the RH in a good zone but that will change when ambient temp/RH are higher
After taking today's pics [/FONT][/FONT] (look at all the new leafs) [FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif]I decided to move the now 3"+ seedling to the front. [/FONT][/FONT][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif]First pic is with fog[/FONT]
Damn, the temp monitor is barely readable- RH 64%, AB was ~ 66*s[/FONT][/FONT]
View attachment 351333 View attachment 351334
[/FONT][/FONT][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif]
Reveg Tent
[/FONT][/FONT][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif]I decided to turn the humidifier off over night, thinking without light (the 4 TLs create very little heat) + cool morning temp 53*s, that I just might be wasting water and electricity. RH was 54%
Tent temps now 65*. After running the humidifier for 5 minutes, RH quickly rose to 75%, which may be too high for the ambient temperature, as ideal RH range is ~ 75%, but that's when temp is between 75-85*, so it's likely a sliding scale. Dunno, but will investigate.
Seems like 5/5 o/o keeps the RH in a good zone but that will change when ambient temp/RH are higher
After taking today's pics [/FONT][/FONT] (look at all the new leafs) [FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif]I decided to move the now 3"+ seedling to the front. [/FONT][/FONT][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif]First pic is with fog[/FONT]
Damn, the temp monitor is barely readable- RH 64%, AB was ~ 66*s[/FONT][/FONT]
View attachment 351333 View attachment 351334
[FONT=Arial, Helvetica, sans-serif]When taking pics first thing this morning...
Notice anything missing?
Seems I need to fire my guard crab
Still don't see it?
Fucking palmetto bugs must have incredible smell and tracking devices
This is the second time they have eaten my seedlings. Confirmed when I saw one last time crawling toward the plants
So, one batch of either AFGooey or AK47 gone[/FONT]
Notice anything missing?
Seems I need to fire my guard crab
Still don't see it?
Fucking palmetto bugs must have incredible smell and tracking devices
This is the second time they have eaten my seedlings. Confirmed when I saw one last time crawling toward the plants
So, one batch of either AFGooey or AK47 gone[/FONT]
marinemansf
Member
Hey pet!
I just was reading your thread and had an idea for your possible gassing predicament. On my system i installed a basic computer fan on my rez and it helps quite a bit. One, it creates an really nice back pressure through the return lines that keeps fresh air flowing back up and into the buckets and pushes out any unwanted gasses. Works quite well as i did a test with a vape pen and blew smoke into the rez fan and watched it pour out of the bucket lids where the holes are cut. It also helps keep my rez temps 5-8 degrees cooler due to evaporation. Heres a pic.
The battery is hooked up to a 12v battery and a float charger. Works great!
I dont want to dredge up the soil vs hydro thing as its seemed to die down finally, but what about bio buckets where it uses beneficial bacteria? The benes actively fight against pests and infection. And the only thing i have to do is add nutes and check ph every few days. Super easy.
I just was reading your thread and had an idea for your possible gassing predicament. On my system i installed a basic computer fan on my rez and it helps quite a bit. One, it creates an really nice back pressure through the return lines that keeps fresh air flowing back up and into the buckets and pushes out any unwanted gasses. Works quite well as i did a test with a vape pen and blew smoke into the rez fan and watched it pour out of the bucket lids where the holes are cut. It also helps keep my rez temps 5-8 degrees cooler due to evaporation. Heres a pic.
The battery is hooked up to a 12v battery and a float charger. Works great!
I dont want to dredge up the soil vs hydro thing as its seemed to die down finally, but what about bio buckets where it uses beneficial bacteria? The benes actively fight against pests and infection. And the only thing i have to do is add nutes and check ph every few days. Super easy.
Looks like I have a lizard in the room as I found the wings and legs of the offending palmetto bug- the food chain at work
I forgot to turn off the power strip to the humidifier last night. RH was 90 this morning. That's not good as it soaked the starter cubes. Now I have to dry them out a bit
I forgot to turn off the power strip to the humidifier last night. RH was 90 this morning. That's not good as it soaked the starter cubes. Now I have to dry them out a bit
I've paid careful attention to ppms, RH, pH but the life support system (the roots) just aren't regenerating as they should. Consequently, the leaf development is lacking and non existent on the other plant. Once I get healthy seedlings I will probably just pull them
Weather has warmed up considerably which will help with starting more new seeds but I am waiting on a new water Divinia Water before I start more seeds
Weather has warmed up considerably which will help with starting more new seeds but I am waiting on a new water Divinia Water before I start more seeds
Recirculation Basics – Part 3
By Urban Garden Magazine ⋅ April 24, 2010 ⋅ Email This Post ⋅ Print This Post ⋅ Post a comment
Filed Under air circulation, air-flow, airflow, CO2, humidity, Issue 10, Michael Christian, oxygen, temperature, ventilation
What all Hydroponic Growers Need To Know About Nutrient Recirculation
As we’ve learned in part 1 and part 2, in order to grow successfully in a hydroponic system, there are certain basics that always need to be kept in check: otherwise, plant performance inevitably suffers. After covering source water, nutrient and pH, world-renowned hydroponics expert Michael Christan breaks down the final ingredients of a healthy indoor growing environment: oxygen, light, temperature, humidity, air circulation and CO2.
Photos courtesy of AmHydro.
The 5 basics of recirculation and plant performance:
1. Pure source water
2. Balanced nutrient ions/anions (EC)
3. Optimum pH
4. Plentiful oxygen availability
5. Optimum light/temp/humidity/air circulation/CO2
The Importance of Oxygen
It’s obvious that loose, friable soil with organic matter and thriving microbes grows plants much better than tight, clay soil devoid of organic matter. The primary missing ingredient in the latter is air (oxygen) availability.
The air we breathe is composed of gasses: 78% nitrogen (N2), 21% oxygen (02), 0.9% argon (Ar) and 0.03% carbon dioxide (CO2). The one we’re focusing on in this article is oxygen. The action of microbes on organic matter in a loose soil produces air pockets as organic matter is mineralized. These oxygen pockets are crucial to the survival and rapid colonization of healthy microbial populations. When the organic matter in the soil is fully consumed by the microbes and plants have consumed all the minerals, oxygen becomes depleted and, if more organic matter is not reapplied, plant performance slows and pathogenic (anaerobic) microbes can colonize. This condition is best avoided.
In media-based recirculating systems, the O2 is in the media: e.g. rockwool, perlite, grow rocks. Plentiful air space is available even after water is drained from the media. Roots thrive in O2-rich pockets. They are able to produce prolific root systems and plentiful root hairs to increase surface area to better absorb available ions. This is the best reason for using media with porosity. Of course, flood and drain systems suck fresh air into the media when it drains, which is why it’s such a great irrigation system.
In water-based recirculating systems, NFT, DFT and Aeroponics, O2 availability is intrinsic to the design of the system. NFT is a flat-bottomed tube with a shallow nutrient stream moving slowly, keeping root hairs moist and absorbing O2 (see “NFT Gro-Tanks,” UGM009). Aeroponics is misting droplets of water, increasing the surface area many-fold for roots to grow prolific root hairs for ion absorption. It supersaturates the solution with O2. DFT uses air pumps and water temp to keep roots bubbled with 02 and oxygen rich.
The heart of a media-based or water-based recirculating system is the nutrient reservoir. This too requires oxygenation, especially when water temperatures rise. The use of air pumps and air stones on smaller reservoirs and pump-powered eductors (venturis) on larger reservoirs make a big difference in pathogen suppression (nasty fungi and bacteria don’t like O2). This agitation drives ethylene gas from the solution and increases the longevity of the nutrient. Be sure that, if there are reservoir lids, there’s room for air exchange with ambient air in the room or greenhouse. Many commercial growers use fresh outside air in their eductors to keep the nutrient solution optimum.
Dissolved Oxygen (DO) can be measured to determine solubility of oxygen in fresh water. Fresh water at 72°F (22°C) has a DO of 8.7 ppm; at 82°F (28°C) it drops to 8.1 ppm. Salt solutions are lower. As a rule of thumb, every increase of 1ppm in DO is equivalent to an 11°F (12°C) temp drop. The cooler the temp, the higher the DO. You don’t want cold water on plant roots, though. You want 72°F (22°C) water at your roots for most plants.
When we measured DO in our greenhouse reservoirs, we found that a 74°F (23°C) nutrient tank at an EC of 2 had a DO of 6.3 ppm (low because of salts and sitting still). When we turned on an eductor (venturi), which we do in ALL reservoirs, we received a reading of 7.6 ppm. BIG difference. That’s an increase of 1.3 ppm without changing temperature.
Then we add an in-line Mazzei injector in between the tank and the feeder pipe, which raises DO to 8.3 ppm. By the time the water had run down the NFT channel and 18 plants had their way with the O2, with some off-gassing occurring, there was an 8.1 ppm DO left in the nutrient solution going back to the reservoir. That’s what we’re after! Plants thrive at those DO levels. Makes ALL the difference.
Be careful: as water temperatures of salt solutions increase, you must mitigate by adding O2 in the reservoir as well as directly on the roots. If you can’t get the DO level up by mechanical means, then you will most likely require a water chiller, which is expensive but sometimes imperative. If you cannot bring water temps down or increase DO in the nutrient solution, your next action will be disease suppression or inoculating roots with beneficials to out-compete the pathogens that thrive in high temp, low DO water. If you do get a DO meter, get a good one. We use an Extech Model 407510.
Light
Photosynthetically Active Radiation (PAR) light is a fancy term for the wavelengths plants use to vibrate chloroplasts to power the engine of photosynthesis, a vaguely understood process in my opinion. It is said that PAR light is in the 400 to 700 nanometer wavelength range. No big deal if you’re outside or in a well-lit greenhouse. But if you are growing under HID light or using it as a supplement, it certainly is.
Color temperatures of lamps are measured in degrees Kelvin from a color rendering index (CRI). The blue/white side of the spectrum has higher Kelvin temp: 6000K-8000K (MH lamps). The yellow/red side of the spectrum has lower Kelvin temperature: 3000K (HPS lamps). As a rule, the higher the Kelvin temp, the more vegetative the growth. The lower Kelvin temps are used for supplemental and/or flowering light. Different bulbs have different combinations or blends of gasses for better PAR value. Plants can be finicky and prefer one blend of light more than another. Trial and error, sometimes, is the only way to find out what your plants really like.
High Intensity Discharge (HID) lamps produce light when the gases inside the fused alumina tube are heated to the point of evaporation by high voltage electricity. This process forces the metal gasses to throw off a barrage of photons partly in the PAR range. As the bulb burns over time, the metal gasses slowly change form and degrade out of the PAR range. It is not obvious, but plant performance can suffer from lack of the PAR light when there is no shortage of photons to the naked eye. To look at light as a possible limiting factor, keep track of the hours your bulbs have been burning. If you are over the recommended burn range as stated by the manufacturer, that could be what’s compromising your system. Rule of thumb with HPS bulbs is to replace them every 12 months, and MH bulbs every 9 months, with HPS burning 12 hour days, MH burning 18 hour days.
Outside it’s obvious what limits light, like trees. But in greenhouses, if the glazing is dirty, that’s a big deal and that situation just creeps up on you. Depending on what you’re growing and what time of year it is, a dirty film can cut out as much as 30% of available light. If you are using an 85% transmission film and have 30% attributed to dirt, that’s 55%, basically shade cloth. In situations where there is too much light and plants are unable to cope with the leaf temperatures or solar radiation, a white or metallic shade cloth is preferable to black, as black can radiate heat back down on the plant canopy. A simple mistake easily avoided by many growers in double poly greenhouses is that the inflation fan is pulling inside air in between the films, thereby creating moisture that blocks light. You can tell by the droplets in between the films, or a haze. It is always recommended to use outside air for inflation. Of course, all of this is dependent on location, latitude, geography, plant in cultivation and skill/experience of the grower. We cannot cover all those variables in a brief article.
Temperature
Plant response to temperature is pretty obvious. It’s visible. Plants stop growing when root temps hit 58°F (14°C). Air temp can actually be cooler than 58°F, but when roots are cool, growth slows and stops even when air temp increases. When temps are too high, say 95°F (35°C) plus, depending on RH, air flow, light, kind, size, and age of a plant, they may stop feeding and spend their energy evaporating water from their stomata to cool down. Temperature must be managed to keep plants transpiring and active in the sweet spot.
Most temp controllers are effective, turning on fans for increased air exchanges, but when temps are too hot outside, air conditioners must be used. As a variable, though, temperature control is straightforward. It’s common knowledge that insects like very consistent temperatures and no air movement. Find which temperatures are your best high and low, and vary them morning, daytime and night. Keep an inhospitable environment for the pests without sacrificing plant performance: another dance to master.
Humidity
The two ways of explaining humidity are relative humidity (RH) and vapor pressure deficit (VPD). Most people are familiar with RH and use hygrometers so, for the purposes of this article, I will use RH.
In my experience, this is the one variable that most growers need to be more aware of. The dance between temp/humidity directly affects transpiration rates as poor transpiration opens the plant organism to disease and mineral deficiencies.
RH is the amount of water vapor present in the air expressed as a % of the amount needed for saturation at the same temperature. Here’s what that means: if the humidity is too high, e.g. 95% at 75°F, plants cannot transpire or evaporate enough water to pull minerals up the vascular system even with stomata wide open. This usually results in calcium (Ca) deficiency (remember, Ca is a non-mobile element and must be constantly supplied to growing tips) and plant stress, which increases their vulnerability to fungal intrusion.
If humidity is too low, 50% at 75°F, stomata will open in an attempt to evaporate water because of the low pressure around the leaf, but then close up to conserve cell pressure in the leaf. Plants stress as they cannot take in CO2 with closed stomata and growth stops as the plant is just trying to survive without going into wilt (i.e. loss of leaf turgidity from which it’s difficult to recover). Again the plant is vulnerable to disease and insects. These two extremes points will create a high probability of crop loss.
As a rule, at 75°F (24°C), if RH is below 60% you must add moisture to get to 75% (which is ideal), but stay below 85% to avoid stress and disease. At 85°F (29°C), if RH is below 70% you must add moisture to get to 80% (which is ideal), but stay below 90% to avoid stress and disease. As temperature rises, air holds less moisture. Steer your plants within these parameters for optimum plant performance.
When RH is too low, use a fogger or humidifier coupled with outside air exchanges. When outside air is too warm and dry, you will have to use some form of air conditioner (if that is the only way) to drop the temperature to increase the moisture-holding capacity of the air.
When RH is too high, raise temperature to reduce moisture saturation of air coupled with outside air exchanges. If outside air has too high of an RH, you will need a dehumidifier to pull water out of the air.
Transpiration is king. Monitoring transpiration rates and keeping them optimum with temp/RH manipulation is crucial. If you are outside of the temp/RH safe zones and don’t use some mechanical method of bringing them under control, you will always be fighting the results of that variable being unchecked. This is where high quality environmental controllers come in handy
You can buy the most expensive nutrients, goodies and gadgets available to grow your crop, but if your plants are unable to transpire and you don’t know that, you had best learn quickly or get a day job
Air Circulation and CO2
No matter what kind of controlled environment you’re running, greenhouse or greenroom, air circulation is another key component that is often overlooked until mildew takes out your crop or your plants starve from lack of CO2. The great outdoors takes care of all this, but inside you have to provide the controls or fall prey to what you didn’t know you didn’t know.
Rule of thumb: 60 air exchanges per hour. Not only do you need to flutter your plants with gentle breezes from an oscillating fan or horizontal air flow (HAF) fans in a greenhouse, but you must freshen the air with air exchanges from outside, taking advantage of the 385 ppm ambient CO2. The raw materials that PAR light makes into carbohydrates are CO2 and H2O. CO2 furnishes the carbon and oxygen, while water furnishes the hydrogen for the carbohydrate (CH2O).
If air exchanges are frequent, 385 ppm CO2 is plenty unless you’re looking to accelerate growth by enriching your space with higher levels to, say, 1500 ppm CO2. Even if you are adding CO2, you still must exchange air. There are numerous ways to provide CO2: chemical reactions, gas bottles, gas generators and a variety of controllers and monitors depending on the size of the operation. For the purpose of this article, you just need to know that it is a basic component of the indoor growing environment, and be mindful that it’s always available. Without CO2, plants will not grow.
One of my teachers, Grenville Stocker in NZ, took me into one of his client’s lettuce/herb greenhouses and asked me, “Would you get a chair, sit down, read a book or hang out in here all day?” Actually, it was way too moist, not enough air movement, my shirt was sticky, and it was uncomfortably warm. I said, “No way.” He remarked, “How do you think those plants feel? The same way, I reckon, except they can’t leave.” Then he showed me powdery mildew in certain areas, a thrip infestation and tip burn in some of the lettuces. The plants did not look vital, they looked stressed. I noticed the HAF fans were down, because of a blown breaker that the grower had been meaning to fix for a week. He had an RH monitor but no controller to check humidity and spill air or add heat … AND he was doing only 1 air exchange per hour because it was cold outside. He wanted to keep temps up inside without turning on the heat, which would cost him money. I looked at the RH: it was 95%. Temp was 80°F but it felt like 90°F because of the humidity. His client was too busy to pay attention or take coaching, and he wasn’t even there. Grenville always tested me; he’d say, “What’s wrong with this picture?” Then he would point out a basic that was obvious once I saw it. Most problems were easy to correct once distinguished.
I found out later the grower lost 50% of his crop and the other 50% was barely marketable. Had he kept HAF fans working, increased his air exchanges and turned up the heat to drive off the humidity with the help of a controller, he would not have had crop and financial loss. Just that one error cost him a market: he couldn’t deliver, so a competitor moved in. The point I’m making is: don’t leave your plants in an environment you can’t handle being in yourself. Use meters and controllers, but always keep them honest by paying attention to what your skin says.
All the variables of light, temperature, humidity, air circulation and CO2 must dance together in a harmony that you must monitor and control to be successful and avoid crop loss. If you cannot distinguish which variable is out, you will be guessing what the problem is and perhaps taking actions that are detrimental. Next time a problem arises (which inevitably will happen) and you’re scratching your head as to what to do, go through this list and check off each one that you KNOW is in tolerance. These 5 basics could be what you didn’t know you didn’t know. Now that you do, dissect them and become competent with each one:
The 5 basics of recirculation and plant performance:
1. Pure source water
2. Balanced nutrient ions/anions (EC)
3. Optimum pH
4. Plentiful oxygen availability
5. Optimum light/temp/humidity/air circulation/CO2
For the content and experiences that allowed me to write these articles, I’d like to thank my teachers, Grenville Stocker (Stocker Hort), Jeff Broad (AutoGrow), Genaro Calabrese (ex partner), Grant Creevey (Accent Hydro) and all our clients and associates for sharing and being open to “figuring it out.” Controlled environment plant cultivation is infinitely beguiling; I am always learning a greater respect for being part of that process. Genaro’s motto: “Every plant, every day.”
Good luck and good growing.
Michael Christian, the president of American Hydroponics since 1984, is a hydroponic system designer and consultant to commercial growers worldwide.
By Urban Garden Magazine ⋅ April 24, 2010 ⋅ Email This Post ⋅ Print This Post ⋅ Post a comment
Filed Under air circulation, air-flow, airflow, CO2, humidity, Issue 10, Michael Christian, oxygen, temperature, ventilation
What all Hydroponic Growers Need To Know About Nutrient Recirculation
As we’ve learned in part 1 and part 2, in order to grow successfully in a hydroponic system, there are certain basics that always need to be kept in check: otherwise, plant performance inevitably suffers. After covering source water, nutrient and pH, world-renowned hydroponics expert Michael Christan breaks down the final ingredients of a healthy indoor growing environment: oxygen, light, temperature, humidity, air circulation and CO2.
Photos courtesy of AmHydro.
The 5 basics of recirculation and plant performance:
1. Pure source water
2. Balanced nutrient ions/anions (EC)
3. Optimum pH
4. Plentiful oxygen availability
5. Optimum light/temp/humidity/air circulation/CO2
The Importance of Oxygen
It’s obvious that loose, friable soil with organic matter and thriving microbes grows plants much better than tight, clay soil devoid of organic matter. The primary missing ingredient in the latter is air (oxygen) availability.
The air we breathe is composed of gasses: 78% nitrogen (N2), 21% oxygen (02), 0.9% argon (Ar) and 0.03% carbon dioxide (CO2). The one we’re focusing on in this article is oxygen. The action of microbes on organic matter in a loose soil produces air pockets as organic matter is mineralized. These oxygen pockets are crucial to the survival and rapid colonization of healthy microbial populations. When the organic matter in the soil is fully consumed by the microbes and plants have consumed all the minerals, oxygen becomes depleted and, if more organic matter is not reapplied, plant performance slows and pathogenic (anaerobic) microbes can colonize. This condition is best avoided.
In media-based recirculating systems, the O2 is in the media: e.g. rockwool, perlite, grow rocks. Plentiful air space is available even after water is drained from the media. Roots thrive in O2-rich pockets. They are able to produce prolific root systems and plentiful root hairs to increase surface area to better absorb available ions. This is the best reason for using media with porosity. Of course, flood and drain systems suck fresh air into the media when it drains, which is why it’s such a great irrigation system.
In water-based recirculating systems, NFT, DFT and Aeroponics, O2 availability is intrinsic to the design of the system. NFT is a flat-bottomed tube with a shallow nutrient stream moving slowly, keeping root hairs moist and absorbing O2 (see “NFT Gro-Tanks,” UGM009). Aeroponics is misting droplets of water, increasing the surface area many-fold for roots to grow prolific root hairs for ion absorption. It supersaturates the solution with O2. DFT uses air pumps and water temp to keep roots bubbled with 02 and oxygen rich.
The heart of a media-based or water-based recirculating system is the nutrient reservoir. This too requires oxygenation, especially when water temperatures rise. The use of air pumps and air stones on smaller reservoirs and pump-powered eductors (venturis) on larger reservoirs make a big difference in pathogen suppression (nasty fungi and bacteria don’t like O2). This agitation drives ethylene gas from the solution and increases the longevity of the nutrient. Be sure that, if there are reservoir lids, there’s room for air exchange with ambient air in the room or greenhouse. Many commercial growers use fresh outside air in their eductors to keep the nutrient solution optimum.
Dissolved Oxygen (DO) can be measured to determine solubility of oxygen in fresh water. Fresh water at 72°F (22°C) has a DO of 8.7 ppm; at 82°F (28°C) it drops to 8.1 ppm. Salt solutions are lower. As a rule of thumb, every increase of 1ppm in DO is equivalent to an 11°F (12°C) temp drop. The cooler the temp, the higher the DO. You don’t want cold water on plant roots, though. You want 72°F (22°C) water at your roots for most plants.
When we measured DO in our greenhouse reservoirs, we found that a 74°F (23°C) nutrient tank at an EC of 2 had a DO of 6.3 ppm (low because of salts and sitting still). When we turned on an eductor (venturi), which we do in ALL reservoirs, we received a reading of 7.6 ppm. BIG difference. That’s an increase of 1.3 ppm without changing temperature.
Then we add an in-line Mazzei injector in between the tank and the feeder pipe, which raises DO to 8.3 ppm. By the time the water had run down the NFT channel and 18 plants had their way with the O2, with some off-gassing occurring, there was an 8.1 ppm DO left in the nutrient solution going back to the reservoir. That’s what we’re after! Plants thrive at those DO levels. Makes ALL the difference.
Be careful: as water temperatures of salt solutions increase, you must mitigate by adding O2 in the reservoir as well as directly on the roots. If you can’t get the DO level up by mechanical means, then you will most likely require a water chiller, which is expensive but sometimes imperative. If you cannot bring water temps down or increase DO in the nutrient solution, your next action will be disease suppression or inoculating roots with beneficials to out-compete the pathogens that thrive in high temp, low DO water. If you do get a DO meter, get a good one. We use an Extech Model 407510.
Light
Photosynthetically Active Radiation (PAR) light is a fancy term for the wavelengths plants use to vibrate chloroplasts to power the engine of photosynthesis, a vaguely understood process in my opinion. It is said that PAR light is in the 400 to 700 nanometer wavelength range. No big deal if you’re outside or in a well-lit greenhouse. But if you are growing under HID light or using it as a supplement, it certainly is.
Color temperatures of lamps are measured in degrees Kelvin from a color rendering index (CRI). The blue/white side of the spectrum has higher Kelvin temp: 6000K-8000K (MH lamps). The yellow/red side of the spectrum has lower Kelvin temperature: 3000K (HPS lamps). As a rule, the higher the Kelvin temp, the more vegetative the growth. The lower Kelvin temps are used for supplemental and/or flowering light. Different bulbs have different combinations or blends of gasses for better PAR value. Plants can be finicky and prefer one blend of light more than another. Trial and error, sometimes, is the only way to find out what your plants really like.
High Intensity Discharge (HID) lamps produce light when the gases inside the fused alumina tube are heated to the point of evaporation by high voltage electricity. This process forces the metal gasses to throw off a barrage of photons partly in the PAR range. As the bulb burns over time, the metal gasses slowly change form and degrade out of the PAR range. It is not obvious, but plant performance can suffer from lack of the PAR light when there is no shortage of photons to the naked eye. To look at light as a possible limiting factor, keep track of the hours your bulbs have been burning. If you are over the recommended burn range as stated by the manufacturer, that could be what’s compromising your system. Rule of thumb with HPS bulbs is to replace them every 12 months, and MH bulbs every 9 months, with HPS burning 12 hour days, MH burning 18 hour days.
Outside it’s obvious what limits light, like trees. But in greenhouses, if the glazing is dirty, that’s a big deal and that situation just creeps up on you. Depending on what you’re growing and what time of year it is, a dirty film can cut out as much as 30% of available light. If you are using an 85% transmission film and have 30% attributed to dirt, that’s 55%, basically shade cloth. In situations where there is too much light and plants are unable to cope with the leaf temperatures or solar radiation, a white or metallic shade cloth is preferable to black, as black can radiate heat back down on the plant canopy. A simple mistake easily avoided by many growers in double poly greenhouses is that the inflation fan is pulling inside air in between the films, thereby creating moisture that blocks light. You can tell by the droplets in between the films, or a haze. It is always recommended to use outside air for inflation. Of course, all of this is dependent on location, latitude, geography, plant in cultivation and skill/experience of the grower. We cannot cover all those variables in a brief article.
Temperature
Plant response to temperature is pretty obvious. It’s visible. Plants stop growing when root temps hit 58°F (14°C). Air temp can actually be cooler than 58°F, but when roots are cool, growth slows and stops even when air temp increases. When temps are too high, say 95°F (35°C) plus, depending on RH, air flow, light, kind, size, and age of a plant, they may stop feeding and spend their energy evaporating water from their stomata to cool down. Temperature must be managed to keep plants transpiring and active in the sweet spot.
Most temp controllers are effective, turning on fans for increased air exchanges, but when temps are too hot outside, air conditioners must be used. As a variable, though, temperature control is straightforward. It’s common knowledge that insects like very consistent temperatures and no air movement. Find which temperatures are your best high and low, and vary them morning, daytime and night. Keep an inhospitable environment for the pests without sacrificing plant performance: another dance to master.
Humidity
The two ways of explaining humidity are relative humidity (RH) and vapor pressure deficit (VPD). Most people are familiar with RH and use hygrometers so, for the purposes of this article, I will use RH.
In my experience, this is the one variable that most growers need to be more aware of. The dance between temp/humidity directly affects transpiration rates as poor transpiration opens the plant organism to disease and mineral deficiencies.
RH is the amount of water vapor present in the air expressed as a % of the amount needed for saturation at the same temperature. Here’s what that means: if the humidity is too high, e.g. 95% at 75°F, plants cannot transpire or evaporate enough water to pull minerals up the vascular system even with stomata wide open. This usually results in calcium (Ca) deficiency (remember, Ca is a non-mobile element and must be constantly supplied to growing tips) and plant stress, which increases their vulnerability to fungal intrusion.
If humidity is too low, 50% at 75°F, stomata will open in an attempt to evaporate water because of the low pressure around the leaf, but then close up to conserve cell pressure in the leaf. Plants stress as they cannot take in CO2 with closed stomata and growth stops as the plant is just trying to survive without going into wilt (i.e. loss of leaf turgidity from which it’s difficult to recover). Again the plant is vulnerable to disease and insects. These two extremes points will create a high probability of crop loss.
As a rule, at 75°F (24°C), if RH is below 60% you must add moisture to get to 75% (which is ideal), but stay below 85% to avoid stress and disease. At 85°F (29°C), if RH is below 70% you must add moisture to get to 80% (which is ideal), but stay below 90% to avoid stress and disease. As temperature rises, air holds less moisture. Steer your plants within these parameters for optimum plant performance.
When RH is too low, use a fogger or humidifier coupled with outside air exchanges. When outside air is too warm and dry, you will have to use some form of air conditioner (if that is the only way) to drop the temperature to increase the moisture-holding capacity of the air.
When RH is too high, raise temperature to reduce moisture saturation of air coupled with outside air exchanges. If outside air has too high of an RH, you will need a dehumidifier to pull water out of the air.
Transpiration is king. Monitoring transpiration rates and keeping them optimum with temp/RH manipulation is crucial. If you are outside of the temp/RH safe zones and don’t use some mechanical method of bringing them under control, you will always be fighting the results of that variable being unchecked. This is where high quality environmental controllers come in handy
You can buy the most expensive nutrients, goodies and gadgets available to grow your crop, but if your plants are unable to transpire and you don’t know that, you had best learn quickly or get a day job
Air Circulation and CO2
No matter what kind of controlled environment you’re running, greenhouse or greenroom, air circulation is another key component that is often overlooked until mildew takes out your crop or your plants starve from lack of CO2. The great outdoors takes care of all this, but inside you have to provide the controls or fall prey to what you didn’t know you didn’t know.
Rule of thumb: 60 air exchanges per hour. Not only do you need to flutter your plants with gentle breezes from an oscillating fan or horizontal air flow (HAF) fans in a greenhouse, but you must freshen the air with air exchanges from outside, taking advantage of the 385 ppm ambient CO2. The raw materials that PAR light makes into carbohydrates are CO2 and H2O. CO2 furnishes the carbon and oxygen, while water furnishes the hydrogen for the carbohydrate (CH2O).
If air exchanges are frequent, 385 ppm CO2 is plenty unless you’re looking to accelerate growth by enriching your space with higher levels to, say, 1500 ppm CO2. Even if you are adding CO2, you still must exchange air. There are numerous ways to provide CO2: chemical reactions, gas bottles, gas generators and a variety of controllers and monitors depending on the size of the operation. For the purpose of this article, you just need to know that it is a basic component of the indoor growing environment, and be mindful that it’s always available. Without CO2, plants will not grow.
One of my teachers, Grenville Stocker in NZ, took me into one of his client’s lettuce/herb greenhouses and asked me, “Would you get a chair, sit down, read a book or hang out in here all day?” Actually, it was way too moist, not enough air movement, my shirt was sticky, and it was uncomfortably warm. I said, “No way.” He remarked, “How do you think those plants feel? The same way, I reckon, except they can’t leave.” Then he showed me powdery mildew in certain areas, a thrip infestation and tip burn in some of the lettuces. The plants did not look vital, they looked stressed. I noticed the HAF fans were down, because of a blown breaker that the grower had been meaning to fix for a week. He had an RH monitor but no controller to check humidity and spill air or add heat … AND he was doing only 1 air exchange per hour because it was cold outside. He wanted to keep temps up inside without turning on the heat, which would cost him money. I looked at the RH: it was 95%. Temp was 80°F but it felt like 90°F because of the humidity. His client was too busy to pay attention or take coaching, and he wasn’t even there. Grenville always tested me; he’d say, “What’s wrong with this picture?” Then he would point out a basic that was obvious once I saw it. Most problems were easy to correct once distinguished.
I found out later the grower lost 50% of his crop and the other 50% was barely marketable. Had he kept HAF fans working, increased his air exchanges and turned up the heat to drive off the humidity with the help of a controller, he would not have had crop and financial loss. Just that one error cost him a market: he couldn’t deliver, so a competitor moved in. The point I’m making is: don’t leave your plants in an environment you can’t handle being in yourself. Use meters and controllers, but always keep them honest by paying attention to what your skin says.
All the variables of light, temperature, humidity, air circulation and CO2 must dance together in a harmony that you must monitor and control to be successful and avoid crop loss. If you cannot distinguish which variable is out, you will be guessing what the problem is and perhaps taking actions that are detrimental. Next time a problem arises (which inevitably will happen) and you’re scratching your head as to what to do, go through this list and check off each one that you KNOW is in tolerance. These 5 basics could be what you didn’t know you didn’t know. Now that you do, dissect them and become competent with each one:
The 5 basics of recirculation and plant performance:
1. Pure source water
2. Balanced nutrient ions/anions (EC)
3. Optimum pH
4. Plentiful oxygen availability
5. Optimum light/temp/humidity/air circulation/CO2
For the content and experiences that allowed me to write these articles, I’d like to thank my teachers, Grenville Stocker (Stocker Hort), Jeff Broad (AutoGrow), Genaro Calabrese (ex partner), Grant Creevey (Accent Hydro) and all our clients and associates for sharing and being open to “figuring it out.” Controlled environment plant cultivation is infinitely beguiling; I am always learning a greater respect for being part of that process. Genaro’s motto: “Every plant, every day.”
Good luck and good growing.
Michael Christian, the president of American Hydroponics since 1984, is a hydroponic system designer and consultant to commercial growers worldwide.
I'm thinking to revisit fogponics. Two of the biggest issues I had was heat and high ppms. Too much heat will affect the roots while ppms above 300 quickly kill the ceramic discs
Will cannabis bud without high ppms? Yes. I am seeing this first hand with my reveg
This time I will keep ppms < 300 and by using a deep cycle timer I might be able to keep the temps down
First I have to go through my stash of foggers to see whether any still work
Stay tuned
Will cannabis bud without high ppms? Yes. I am seeing this first hand with my reveg
This time I will keep ppms < 300 and by using a deep cycle timer I might be able to keep the temps down
First I have to go through my stash of foggers to see whether any still work
Stay tuned
