RM - aquagrower
Active member
VT, here's my hypothisis:
1) we know that the max sat point decreases as the temp rises.
2) we know that a larger root system will have a higher O2 consumption rate than a smaller root system
3) we know that our plants grow fastest at 78 F
taking those 3 things into account, we van theorize that it's possable for a mature plant (with a large root zone) to consume all available O2 in the rez, leading to an anaerobic condition, leading to root rot.
who knows tho, could be that i've just smoked too much.
1) we know that the max sat point decreases as the temp rises.
2) we know that a larger root system will have a higher O2 consumption rate than a smaller root system
3) we know that our plants grow fastest at 78 F
taking those 3 things into account, we van theorize that it's possable for a mature plant (with a large root zone) to consume all available O2 in the rez, leading to an anaerobic condition, leading to root rot.
who knows tho, could be that i've just smoked too much.
RM - aquagrower
Active member
cool, if it's in the FAQ, then i can find it. just want to be sure that it matches up with the chart that i found. good to verify that type of shit, imo.
good ole sqrints, he posts here, at ic, under another name.
good ole sqrints, he posts here, at ic, under another name.
G
Guest
That plants get too big and take too much O2. Definately. But, you needn't have a definitive guide rather a 'this much works for this many big ass plants so here's hoping they all get that big' approach and then factor another 25% to be sure. Too much O2 will just bubble away I'm sure there's an extreme limit (say all your fish are sideways floating on said bubbles)
That said count your plants, get the bio figures for that many plants, add waterfall, and you will be ok. but add more, in case magic shit happens at 6 months hehe.
That said count your plants, get the bio figures for that many plants, add waterfall, and you will be ok. but add more, in case magic shit happens at 6 months hehe.
G
Guest
hi, for those interested in DO numbers here's a link: http://www.fivecreeks.org/monitor/do.html
there's a calulator at the bottom of the page that includes altitude/pressure in the equation, which is also a very important factor.
78F converts to 25.6C
there's a calulator at the bottom of the page that includes altitude/pressure in the equation, which is also a very important factor.
78F converts to 25.6C
G
Guest
Thank you that's a handy link now a bookmark.
A picture for VT seeing as you like learning here.
LOOK HOW DUMB I AM.
I had a mildew and humidity problem so I installed 2 new fans. One above the res to remove the humid air churned in there - works great! The other a BIGASS fan placed as a turbo on the ducting of the other outlet.
And here's the inlet. What a NOOB! Rofl!
That plant has to sit up on something like that to allow room for air roots. Meantime the airflow gets a continuous wick of water to fan directly under my plants.
But it's not all bad
A picture for VT seeing as you like learning here.
LOOK HOW DUMB I AM.
I had a mildew and humidity problem so I installed 2 new fans. One above the res to remove the humid air churned in there - works great! The other a BIGASS fan placed as a turbo on the ducting of the other outlet.
And here's the inlet. What a NOOB! Rofl!
That plant has to sit up on something like that to allow room for air roots. Meantime the airflow gets a continuous wick of water to fan directly under my plants.
But it's not all bad
RM - aquagrower said:
4) and we know the plant's requirement for DO (Dissolved Oxygen) INCREASES as root zone temps increase....so...higher temps = less DO AND higher temps = more DO required by plant ... in short...BAD COMBO
SatGhost Thanks for sharing
Nice post TH... having that intake down there helps those stalks fatten up looks like-VT-
Last edited:
G
Guest
They've been fat like that 18 months in the bud side. The intake installed 2 ish months ago. Mildew still tries to take hold skim milk works but leaves residue, maybe a spray then a spritz...
I'm thinking I'll run the gauntlet with that barrel see if I can do no res changes for 10 years. Hell, why not!
I'm thinking I'll run the gauntlet with that barrel see if I can do no res changes for 10 years. Hell, why not!
G
Guest
Ground insulation for barrels/tanks/res. More than likely covered by some clever grower trying to get res temps down.
Should you have the luxury of sinking your water into the ground a layer of polystyrene around it will provide added thermal stability.
Should you have the luxury of sinking your water into the ground a layer of polystyrene around it will provide added thermal stability.
BakedBeans
Member
I really want large tanks of catfish and bass now. Just got back from Cabelas and those things are awesome. 
RM - aquagrower
Active member
BB,
catfish i know thrive in aqua. my little red tail cat was about 4 inches when i got him about a year ago. now the bastard is about a foot long, and i'm pretty sure that he recently ate my 6" pleco.
as for bass, met a guy at the pet store in line to get feeders. said he had a big bass in a 125 gal tank. said the fucker went thru 300 1-2" feeders per week. that's about $25 every week.
hell, maybe the thing to do is turn the guys at Cabelas on to an aqua stsyem.
catfish i know thrive in aqua. my little red tail cat was about 4 inches when i got him about a year ago. now the bastard is about a foot long, and i'm pretty sure that he recently ate my 6" pleco.
as for bass, met a guy at the pet store in line to get feeders. said he had a big bass in a 125 gal tank. said the fucker went thru 300 1-2" feeders per week. that's about $25 every week.
hell, maybe the thing to do is turn the guys at Cabelas on to an aqua stsyem.
BakedBeans
Member
Hmm, man. That's a lot of fish (the feeders). Maybe I should aim for growing small to mid-sized bass, and then like, grow them big and sell them for ponds or lake.
Catfish, hmm. The right kind would make a great food source, not only for my family but I could cater to local restaraunts or something. I'm sure something could be worked out with someone to deliver live catfish. Hah, that would be kinda neat to pick your fish and then eat it.. OK, so maybe only down here in the south.
Hey, one question I do have since I'm really contemplating a tank purchase very soon (or at least some sort of pond). Should I just start out building my own bio-filter? I would rather spend as little as I could on the aquaculture side by using cheap fish and equipment, but of course, I don't want to half-ass it. I know you built your own larger filter. Any links to other designs or at least some filter theory? I don't even know where to start on the aqua forums. I'll keep trying though.
Catfish, hmm. The right kind would make a great food source, not only for my family but I could cater to local restaraunts or something. I'm sure something could be worked out with someone to deliver live catfish. Hah, that would be kinda neat to pick your fish and then eat it.. OK, so maybe only down here in the south.
Hey, one question I do have since I'm really contemplating a tank purchase very soon (or at least some sort of pond). Should I just start out building my own bio-filter? I would rather spend as little as I could on the aquaculture side by using cheap fish and equipment, but of course, I don't want to half-ass it. I know you built your own larger filter. Any links to other designs or at least some filter theory? I don't even know where to start on the aqua forums. I'll keep trying though.
The OG FAQ had something on a bio-filter, which is how I originally opened my mind to this....that and an aqua enthusiasts' participation in my OG thread.
Dank
Good stuff guys...my fascination with aquaponics is unabated, inexorable....growing catfish....then harvesting buds AND fish for the family?
Dank
RM - aquagrower
Active member
what size tank are ya looking at getting? and have ya ever kept fish before? if ya haven't expect to loose some. i would buy good equipment, and cheap fish. it's way easier to upgrade fish, then rebuild the system. i started my big tank going over 2 years ago, and ain't drained it yet.
as for bio-filters, this is where me and TH disagree. he believes that having too much bio-filter is a waste, and wil rob you of resourses (O2, food, ect). i believe that the bio-filter is simply a suitable home for BB, kind of like a high rise apt building, and that the little guys will only move in large numbers if there's something for them to eat. i don't think that ya can have too much bio filtration, as long as ya keep good DO levels.
as for bio-filters, this is where me and TH disagree. he believes that having too much bio-filter is a waste, and wil rob you of resourses (O2, food, ect). i believe that the bio-filter is simply a suitable home for BB, kind of like a high rise apt building, and that the little guys will only move in large numbers if there's something for them to eat. i don't think that ya can have too much bio filtration, as long as ya keep good DO levels.
BakedBeans
Member
Well, what I want, what I'm willing to settle for, and what I end up are most likely all different things right now.
I want a 100gal (or thereabouts) for this very long wall in my living room (which isn't even used as a room, it's a playroom for the kiddos). On the other side of the wall is my hidden under-stairs closet and would be a great place to house a veg room and/or some pump equipment. On the other, other side of the wall (a T) is the garage with my cabinet. I'm just not quite sure I want to go through cutting up sheetrock in this house yet.
I just terminated my first grow after 5 weeks. I just wasn't doing it up to my own standards (no money for equipment), and that made it half-assed. Despite my best efforts to fuck it all up, my plants were healthy and up to 1 1/2 feet tall (Blue Mystic @ 6 weeks from seed). I was growing in coco with Pureblend Pro and mixed in mychorrizae and rare earth (a free sample). This was under 4x4ft cheap flouros. It was getting up to 90 degrees in the garage and flies were multiplying (I had no ventilation, so I couldn't shut the doors).
I just said screw it and shut it all down. I'm better than that and I am only out $30 in seeds and a month and a half. Oh, I tried some AK-48 (these are both Nirvana strains) and they sucked big time. Only 3 germinated and only two really ever grew (and very slowly at that). The Blue Mystic literally popped open and grew tail floating at the top of a cup of water overnight. I had to plant them within 36 hours of the beginning of germination.
Ugh, sorry to run off topic there, I've had a trying few months, but it's getting much better. I'm gunning for an outside pond for legal herbs and veggies. Something that will fit on the porch right now. I'm going to switch to aquapot as soon as I get a real grow setup. I'm working on it, just taking it a little slower now. I don't want to screw it up.
I want at least 100gal worth of fishwater, and will start with cheapies and grow them right. I will most likely setup bio-buckets, since it is a similar concept and I think will be very adaptable to an aqua grow. Once I dial in both systems separately, I will connect them, and with a little planning, everything will go smoothly. I plan on renting a house or apartment or something for this. Most likely a house so I can have a garage to pull into.
For right now, I'll just do a pond and maybe a small tank inside the house. It'll keep the kiddos interested for about 5 minutes, maybe.
I want a 100gal (or thereabouts) for this very long wall in my living room (which isn't even used as a room, it's a playroom for the kiddos). On the other side of the wall is my hidden under-stairs closet and would be a great place to house a veg room and/or some pump equipment. On the other, other side of the wall (a T) is the garage with my cabinet. I'm just not quite sure I want to go through cutting up sheetrock in this house yet.
I just terminated my first grow after 5 weeks. I just wasn't doing it up to my own standards (no money for equipment), and that made it half-assed. Despite my best efforts to fuck it all up, my plants were healthy and up to 1 1/2 feet tall (Blue Mystic @ 6 weeks from seed). I was growing in coco with Pureblend Pro and mixed in mychorrizae and rare earth (a free sample). This was under 4x4ft cheap flouros. It was getting up to 90 degrees in the garage and flies were multiplying (I had no ventilation, so I couldn't shut the doors).
I just said screw it and shut it all down. I'm better than that and I am only out $30 in seeds and a month and a half. Oh, I tried some AK-48 (these are both Nirvana strains) and they sucked big time. Only 3 germinated and only two really ever grew (and very slowly at that). The Blue Mystic literally popped open and grew tail floating at the top of a cup of water overnight. I had to plant them within 36 hours of the beginning of germination.
Ugh, sorry to run off topic there, I've had a trying few months, but it's getting much better. I'm gunning for an outside pond for legal herbs and veggies. Something that will fit on the porch right now. I'm going to switch to aquapot as soon as I get a real grow setup. I'm working on it, just taking it a little slower now. I don't want to screw it up.
I want at least 100gal worth of fishwater, and will start with cheapies and grow them right. I will most likely setup bio-buckets, since it is a similar concept and I think will be very adaptable to an aqua grow. Once I dial in both systems separately, I will connect them, and with a little planning, everything will go smoothly. I plan on renting a house or apartment or something for this. Most likely a house so I can have a garage to pull into.
For right now, I'll just do a pond and maybe a small tank inside the house. It'll keep the kiddos interested for about 5 minutes, maybe.
muddy waters
Active member
these are interesting theories on bio-filtration that TH and RM have going... i still think if oxygenation is ample, more bio-filter is better, it just means you have the potential to up the fish load if the plant need is there.
baked beans, i commend you for choosing to try to go aqua.
i'm doing a lot of research on aquatic ecosystems, trying to come up with particular combinations of fish and aquatic plants that are especially well suited to not only aquaponics but also permacultural means of feeding, like fish that will eat raw and cooked vegetable matter (people food leftovers: free), worms (worm composting: free), and algae and insect varieties that are naturally present or easily cultured. operating an aquatic ecosystem like this demands more time than just buying whatever. but in actuality despite needing more attention, i think it saves money and time (not to mention that it is ecologically top notch and a form of natural art).
but think about the amount of time spent going to the hydro store, the amount of time spent working to make the money spent on nutes, additives, additional equipment, the amount of time spent mixing or diluting nutes (especially significant outside the N. America/W. Europe), testing pH, the amount of time sterilizing after each grow. these are all part of the cost of hydro, and the only products you get in the end are buds and trash (discarded solution, discarded vegetation, discarded bottles).
in an aquaponic system, and especially a permacultural setup, the products are several (buds, fish, aquatic plant cuttings, hummus, fish feed, worm feed), and the trash produced can be zero or very close to it. the inputs take the form of your own time and energy, but with the proper equipment and layout, all the cultures can take off with just minimal maintenance. establishing the proper conditions demands a lot of attention, some technical know-how, but after that all you do is feed, harvest, and do a little cleaning. and just add water.
baked beans, i commend you for choosing to try to go aqua.
i'm doing a lot of research on aquatic ecosystems, trying to come up with particular combinations of fish and aquatic plants that are especially well suited to not only aquaponics but also permacultural means of feeding, like fish that will eat raw and cooked vegetable matter (people food leftovers: free), worms (worm composting: free), and algae and insect varieties that are naturally present or easily cultured. operating an aquatic ecosystem like this demands more time than just buying whatever. but in actuality despite needing more attention, i think it saves money and time (not to mention that it is ecologically top notch and a form of natural art).
but think about the amount of time spent going to the hydro store, the amount of time spent working to make the money spent on nutes, additives, additional equipment, the amount of time spent mixing or diluting nutes (especially significant outside the N. America/W. Europe), testing pH, the amount of time sterilizing after each grow. these are all part of the cost of hydro, and the only products you get in the end are buds and trash (discarded solution, discarded vegetation, discarded bottles).
in an aquaponic system, and especially a permacultural setup, the products are several (buds, fish, aquatic plant cuttings, hummus, fish feed, worm feed), and the trash produced can be zero or very close to it. the inputs take the form of your own time and energy, but with the proper equipment and layout, all the cultures can take off with just minimal maintenance. establishing the proper conditions demands a lot of attention, some technical know-how, but after that all you do is feed, harvest, and do a little cleaning. and just add water.
What does "up the fish load mean"? Increase the number of fish? Or feed the fish more? This is beginning to sound less complicated to me....so...you feed the fish the right food to produce the by-products (in the fish poop) to feed the plants. If deficiencies show...you add more fish and/or adjust the fish diet? Am I even close?
Great post btw Muddy....
muddy waters
Active member
exactly VT, up the fish load means house more fish, but you're also correct that by varying the diet, you can ensure sufficient supply of macro and micro nutrients. if your fish are eating mainly worms and duckweed that you produce, you can regulate what's introduced into those cultures and know pretty much what's getting to your plants after the fish digest and expel it.
and now a li'l somethin somethin for the eco-nerds:
http://www.hamburger-umweltinst.org/biomass/mnlwide/BNRTOC.html
and now a li'l somethin somethin for the eco-nerds:
http://www.hamburger-umweltinst.org/biomass/mnlwide/BNRTOC.html
RM - aquagrower
Active member
up the fish load usually means add more fish, but more accurately it means to up the load on the bio filter.
and, yea, you got it. once you've got everything dailed in, running this system is as simple as feeding the fish and keeping it topped off with tap water. don't do no rez changes, ever.
this last run was my first with this system. i kept waiting to see deficiencies, but never really did. ph problems i did have were due to my own stupidity.
and, yea, you got it. once you've got everything dailed in, running this system is as simple as feeding the fish and keeping it topped off with tap water. don't do no rez changes, ever.
this last run was my first with this system. i kept waiting to see deficiencies, but never really did. ph problems i did have were due to my own stupidity.
There are a few issues about Dissolved Oxygen and Water Temperature running around in this thread, so although the following is a bit lengthy, i know it will be of
some use to the Aquaponic People so here it is:
Oxygenation, Air Pumps, Nutrient Uptake and Temperatures
Introduction: Why plant roots need oxygen
Oxygen is an essential plant nutrient - plant root systems require oxygen for aerobic respiration, an essential plant process that releases energy for root growth and nutrient uptake. In many 'solution culture' hydroponic systems, the oxygen supplied for plant root uptake is provided mostly as dissolved oxygen (DO) held in the nutrient solution. If depletion of this dissolved oxygen in the root system occurs, then growth of plants, water and mineral uptake are reduced.
Injury from low (or no) oxygen in the root zone can take several forms and these will differ in severity between plant types. Often the first sign of inadequate oxygen supply to the roots is wilting of the plant under warm conditions and high light levels. Insufficient oxygen reduces the permeability of the roots to water and there will be an accumulation of toxins, so that both water and minerals are not absorbed in sufficient amounts to support plant growth. This wilting is accompanied by slower rates of photosynthesis and carbohydrate transfer, so that over time, plant growth is reduced and yields are affected. If oxygen starvation continues, mineral deficiencies will begin to show, roots die back and plants will become stunted. If the lack of oxygen continues in the root zone, plants produce a stress hormone - ethylene, which accumulates in the roots and causes collapse of the root cells, at this stage pathogens such as pythium can easily take hold and destroy the plant.
Oxygen in Hydroponic Nutrient Solutions
While it’s possible to measure the levels of dissolved oxygen in a hydroponic nutrient solution, it’s not carried out as often as EC and pH monitoring due to the cost of accurate DO (Dissolved Oxygen meters). However, if an effective method of aeration is continually being used, and solution temperatures are not reaching excessively high levels, then good levels of oxygenation in most systems can be achieved One of the most common and effective methods of oxygenation in hydroponic nutrient solutions is with the use of air pumps/machines and air stones.
Air Pumps and Air Stones
While there are a number of methods that can be used to introduce oxygen into a nutrient solution, many of these, such as ozone treatment, are expensive and not often used by smaller growers. One of the most practical and inexpensive, yet efficient ways of getting more dissolved oxygen into a plants root system is through forcing air into the nutrient. Air pumps are widely available in a range of sizes, from very small up to very large with capacity to run from one to many `air stones’ each introducing hundreds of tiny bubbles of fresh, oxygen rich air into the nutrient solution.
Why an Air Stone
While an air pump tube alone can bubble air into a nutrient solution, oxygenation or the process of getting atmospheric oxygen dissolved into the liquid nutrient, is much more effective where many tiny bubbles of air are created, rather than a slow stream of larger bubbles. The greater the surface contact between the air bubbles and the nutrient, the more oxygen will diffuse into the nutrient solution and smaller bubbles create a far greater surface area than a few larger bubbles will. Air stones simply break up the air flow and distribute along the surface of the porous 'stone' so that many tiny bubbles are rapidly introduced into the nutrient. Depending on the size or dimensions of the nutrient reservoir into which air is being introduced for oxygenation, air stones of different shapes and sizes can be selected. For small rectangular tanks, long thin air stones (some up to 1 foot in length) can be placed on the base of the reservoir to distribute air bubbles and oxygen uniformly. A larger number of smaller, round, cylindrical or oval air stones placed at equal distance inside a nutrient pool or tank also ensure high levels of oxygenation.
Air stones also have the benefit of acting as 'weights' which remain stable on the base, or in the lower layers of the nutrient tank - the further the bubbles have to travel to reach the surface of the nutrient, the more time oxygen has to diffuse into the liquid and the higher the rates of dissolved oxygen than can be obtained from an air pump and stone set up.
For systems with multiple nutrient reservoirs or tanks, one large air pump with many outlets will allow oxygenation into all systems and it is always a good idea to buy an air machine and air stones larger than currently required so that aeration can be increased under warmer conditions or if the hydroponic system is later expanded.
Oxygen and Temperature Effects - Effective Aeration
While forcing air bubbles deep down into the nutrient reservoir generally increases the dissolved oxygen levels in the nutrient, there is one other major factor to consider and that's the temperature of the air being pumped into the nutrient. As the temperature of a nutrient solution increases, its ability to hold dissolved oxygen decreases. So a cool nutrient solution may in fact hold twice as much oxygen at 'saturation level' than a warm solution. For example a nutrient solution at 45 F can hold around 12ppm of dissolved oxygen at 'saturation', (meaning it is the most it can hold), but the same nutrient solution at a temperature of 85 F will hold less than 7ppm at saturation. This means at a solution temperature of 85F there is much less dissolved oxygen available for the plant’s root system to take up. To complicate matters further, the requirement of the plant’s root system for oxygen at warmer temperatures, is many times greater than at cooler temperatures due to the increased rate of root respiration. So warm nutrients mean a very high oxygen requirement from the plant’s roots, but the nutrient can only hold very limited amounts of dissolved oxygen at saturation, no matter how much air is being bubbled into the solution. Ideally, nutrient solution temperatures for most plants should be run lower than the overall air temperature - this has many beneficial effects on plant growth and development. However, if overly warm air from the growing environment is pumped into an otherwise cool nutrient solution, the warm air will rapidly increase the temperature of the nutrient to that of the growing environment. If air is being pumped via an air machine with an intake close to lights or other heat sources then rapid heating of the nutrient will occur. On the other hand, cool air has the ability to reduce the temperature of the nutrient if sufficient levels are pumped in and thus result in a much more highly oxygenated solution for the plant’s roots. If keeping the nutrient solution temperature down seems to be a continual problem, checking the air inlet temperature of an air pump is a good idea. Overly warm nutrient solutions (ideally nutrient solutions should remain below 65 - 75 F) for most warm season, high light plants and well below 69 F for cool season.can have serious effects on the plants root system. Apart from the increased oxygen requirement due to a much higher rate of root respiration which can rapidly result in oxygen starvation, high solution temperatures favour many of the root disease pathogens. Plant roots become highly 'stressed' when experiencing high temperatures, particularly if there is a large mis-match between the air the root temperature. Root stress slows the development of new roots, resulting in reserves inside the root tissue being `burned up’ during respiration faster than they are accumulated, and stress makes the root system in general more susceptible to disease attack. Keeping a check on nutrient temperature is vital, as is ensuring that air machines are not blasting hot air into the solution and cooking plant roots. Aeration is most effective when cool air is bubbled into a nutrient.
Oxygenation and Nutrient Uptake
Healthy roots supplied with sufficient oxygen are able to absorb nutrient ions selectively from the surrounding solution as required. The metabolic energy which is required to drive this nutrient uptake process is obtained from root respiration using oxygen. In fact there can be a net loss of nutrient ions from a plant’s root system when suffering from a lack of oxygen (anaerobic conditions). Without sufficient oxygen in the root zone, plants are unable to take up mineral nutrients in the concentrations required for maximum growth and development. Maintain maximum levels of dissolved oxygen boosts nutrient uptake by ensuring healthy roots have the energy required to rapidly take up and transport water and mineral ions.
Calcium is one important nutrient ion which has been shown to benefit from high levels of oxygenation in the hydroponic nutrient solution Calcium, unlike the other major nutrients is absorbed mostly by the root growing tips (root apex). The root apex has a large energy requirement for new cell production and growth and is therefore vulnerable to oxygen stress If root tips begin to suffer from a lack of oxygen, a shortage of calcium in the shoot will occur. This shortage of calcium makes the development of calcium disorders such as tip burn and blossom end rot of fruit more likely and severe under oxygen starvation conditions. High levels of oxygenation ensure healthy root tips are able to take the levels of calcium required for new tissue growth and development.
Conclusion
While providing oxygenation with the use of air machines and stones is an excellent method of increasing the dissolved oxygen (DO) levels in a nutrient solution, the temperature of the air intake and nutrient solution must also be managed to ensure oxygen starvation in the root zone does not occur. Pumping hot air into a nutrient not only creates temperature stress in the root zone, it also results in less oxygen carrying capacity in the solution itself - a recipe for root suffocation that will rapidly affect the top portion of the plant as well. Getting oxygenation right means checking both aeration capacity of the equipment being chosen and temperatures in the nutrient and root zone
Dissolved Oxygen Saturation Limits for Water at Sea Level Pressure by Temperature:
32 degrees F...........................14.5 ppm oxygen in water saturated with air
41 degrees F...........................12.7 ppm
50 degrees F...........................11.2 ppm
59 degrees F...........................10.5 ppm
68 degrees F............................9.8 ppm
77 degrees F...........................8.25 ppm
86 degrees F............................7.51 ppm
95 degrees F.............................6.8 ppm
It is important to understand that temperature and pressure are not the only factors that can limit dissolved oxygen content in water. As organisms draw oxygen from water, it must be replaced as quickly as they extract it. In aquariums, it is common practice to bubble air through the water to charge it with oxygen. This is not an especially powerful way to add oxygen to water, but it works with fish tanks that hold only a small amount of fish in many liters of water. A far more effective way to charge water with oxygen is to spray the water through the air, which many hydroponics growers do to supply their rapidly growing plants with the large amount of oxygen they need to remain healthy. (from "The Best of Maximum Yield" p. 26-27)
some use to the Aquaponic People so here it is:
Oxygenation, Air Pumps, Nutrient Uptake and Temperatures
Introduction: Why plant roots need oxygen
Oxygen is an essential plant nutrient - plant root systems require oxygen for aerobic respiration, an essential plant process that releases energy for root growth and nutrient uptake. In many 'solution culture' hydroponic systems, the oxygen supplied for plant root uptake is provided mostly as dissolved oxygen (DO) held in the nutrient solution. If depletion of this dissolved oxygen in the root system occurs, then growth of plants, water and mineral uptake are reduced.
Injury from low (or no) oxygen in the root zone can take several forms and these will differ in severity between plant types. Often the first sign of inadequate oxygen supply to the roots is wilting of the plant under warm conditions and high light levels. Insufficient oxygen reduces the permeability of the roots to water and there will be an accumulation of toxins, so that both water and minerals are not absorbed in sufficient amounts to support plant growth. This wilting is accompanied by slower rates of photosynthesis and carbohydrate transfer, so that over time, plant growth is reduced and yields are affected. If oxygen starvation continues, mineral deficiencies will begin to show, roots die back and plants will become stunted. If the lack of oxygen continues in the root zone, plants produce a stress hormone - ethylene, which accumulates in the roots and causes collapse of the root cells, at this stage pathogens such as pythium can easily take hold and destroy the plant.
Oxygen in Hydroponic Nutrient Solutions
While it’s possible to measure the levels of dissolved oxygen in a hydroponic nutrient solution, it’s not carried out as often as EC and pH monitoring due to the cost of accurate DO (Dissolved Oxygen meters). However, if an effective method of aeration is continually being used, and solution temperatures are not reaching excessively high levels, then good levels of oxygenation in most systems can be achieved One of the most common and effective methods of oxygenation in hydroponic nutrient solutions is with the use of air pumps/machines and air stones.
Air Pumps and Air Stones
While there are a number of methods that can be used to introduce oxygen into a nutrient solution, many of these, such as ozone treatment, are expensive and not often used by smaller growers. One of the most practical and inexpensive, yet efficient ways of getting more dissolved oxygen into a plants root system is through forcing air into the nutrient. Air pumps are widely available in a range of sizes, from very small up to very large with capacity to run from one to many `air stones’ each introducing hundreds of tiny bubbles of fresh, oxygen rich air into the nutrient solution.
Why an Air Stone
While an air pump tube alone can bubble air into a nutrient solution, oxygenation or the process of getting atmospheric oxygen dissolved into the liquid nutrient, is much more effective where many tiny bubbles of air are created, rather than a slow stream of larger bubbles. The greater the surface contact between the air bubbles and the nutrient, the more oxygen will diffuse into the nutrient solution and smaller bubbles create a far greater surface area than a few larger bubbles will. Air stones simply break up the air flow and distribute along the surface of the porous 'stone' so that many tiny bubbles are rapidly introduced into the nutrient. Depending on the size or dimensions of the nutrient reservoir into which air is being introduced for oxygenation, air stones of different shapes and sizes can be selected. For small rectangular tanks, long thin air stones (some up to 1 foot in length) can be placed on the base of the reservoir to distribute air bubbles and oxygen uniformly. A larger number of smaller, round, cylindrical or oval air stones placed at equal distance inside a nutrient pool or tank also ensure high levels of oxygenation.
Air stones also have the benefit of acting as 'weights' which remain stable on the base, or in the lower layers of the nutrient tank - the further the bubbles have to travel to reach the surface of the nutrient, the more time oxygen has to diffuse into the liquid and the higher the rates of dissolved oxygen than can be obtained from an air pump and stone set up.
For systems with multiple nutrient reservoirs or tanks, one large air pump with many outlets will allow oxygenation into all systems and it is always a good idea to buy an air machine and air stones larger than currently required so that aeration can be increased under warmer conditions or if the hydroponic system is later expanded.
Oxygen and Temperature Effects - Effective Aeration
While forcing air bubbles deep down into the nutrient reservoir generally increases the dissolved oxygen levels in the nutrient, there is one other major factor to consider and that's the temperature of the air being pumped into the nutrient. As the temperature of a nutrient solution increases, its ability to hold dissolved oxygen decreases. So a cool nutrient solution may in fact hold twice as much oxygen at 'saturation level' than a warm solution. For example a nutrient solution at 45 F can hold around 12ppm of dissolved oxygen at 'saturation', (meaning it is the most it can hold), but the same nutrient solution at a temperature of 85 F will hold less than 7ppm at saturation. This means at a solution temperature of 85F there is much less dissolved oxygen available for the plant’s root system to take up. To complicate matters further, the requirement of the plant’s root system for oxygen at warmer temperatures, is many times greater than at cooler temperatures due to the increased rate of root respiration. So warm nutrients mean a very high oxygen requirement from the plant’s roots, but the nutrient can only hold very limited amounts of dissolved oxygen at saturation, no matter how much air is being bubbled into the solution. Ideally, nutrient solution temperatures for most plants should be run lower than the overall air temperature - this has many beneficial effects on plant growth and development. However, if overly warm air from the growing environment is pumped into an otherwise cool nutrient solution, the warm air will rapidly increase the temperature of the nutrient to that of the growing environment. If air is being pumped via an air machine with an intake close to lights or other heat sources then rapid heating of the nutrient will occur. On the other hand, cool air has the ability to reduce the temperature of the nutrient if sufficient levels are pumped in and thus result in a much more highly oxygenated solution for the plant’s roots. If keeping the nutrient solution temperature down seems to be a continual problem, checking the air inlet temperature of an air pump is a good idea. Overly warm nutrient solutions (ideally nutrient solutions should remain below 65 - 75 F) for most warm season, high light plants and well below 69 F for cool season.can have serious effects on the plants root system. Apart from the increased oxygen requirement due to a much higher rate of root respiration which can rapidly result in oxygen starvation, high solution temperatures favour many of the root disease pathogens. Plant roots become highly 'stressed' when experiencing high temperatures, particularly if there is a large mis-match between the air the root temperature. Root stress slows the development of new roots, resulting in reserves inside the root tissue being `burned up’ during respiration faster than they are accumulated, and stress makes the root system in general more susceptible to disease attack. Keeping a check on nutrient temperature is vital, as is ensuring that air machines are not blasting hot air into the solution and cooking plant roots. Aeration is most effective when cool air is bubbled into a nutrient.
Oxygenation and Nutrient Uptake
Healthy roots supplied with sufficient oxygen are able to absorb nutrient ions selectively from the surrounding solution as required. The metabolic energy which is required to drive this nutrient uptake process is obtained from root respiration using oxygen. In fact there can be a net loss of nutrient ions from a plant’s root system when suffering from a lack of oxygen (anaerobic conditions). Without sufficient oxygen in the root zone, plants are unable to take up mineral nutrients in the concentrations required for maximum growth and development. Maintain maximum levels of dissolved oxygen boosts nutrient uptake by ensuring healthy roots have the energy required to rapidly take up and transport water and mineral ions.
Calcium is one important nutrient ion which has been shown to benefit from high levels of oxygenation in the hydroponic nutrient solution Calcium, unlike the other major nutrients is absorbed mostly by the root growing tips (root apex). The root apex has a large energy requirement for new cell production and growth and is therefore vulnerable to oxygen stress If root tips begin to suffer from a lack of oxygen, a shortage of calcium in the shoot will occur. This shortage of calcium makes the development of calcium disorders such as tip burn and blossom end rot of fruit more likely and severe under oxygen starvation conditions. High levels of oxygenation ensure healthy root tips are able to take the levels of calcium required for new tissue growth and development.
Conclusion
While providing oxygenation with the use of air machines and stones is an excellent method of increasing the dissolved oxygen (DO) levels in a nutrient solution, the temperature of the air intake and nutrient solution must also be managed to ensure oxygen starvation in the root zone does not occur. Pumping hot air into a nutrient not only creates temperature stress in the root zone, it also results in less oxygen carrying capacity in the solution itself - a recipe for root suffocation that will rapidly affect the top portion of the plant as well. Getting oxygenation right means checking both aeration capacity of the equipment being chosen and temperatures in the nutrient and root zone
Dissolved Oxygen Saturation Limits for Water at Sea Level Pressure by Temperature:
32 degrees F...........................14.5 ppm oxygen in water saturated with air
41 degrees F...........................12.7 ppm
50 degrees F...........................11.2 ppm
59 degrees F...........................10.5 ppm
68 degrees F............................9.8 ppm
77 degrees F...........................8.25 ppm
86 degrees F............................7.51 ppm
95 degrees F.............................6.8 ppm
It is important to understand that temperature and pressure are not the only factors that can limit dissolved oxygen content in water. As organisms draw oxygen from water, it must be replaced as quickly as they extract it. In aquariums, it is common practice to bubble air through the water to charge it with oxygen. This is not an especially powerful way to add oxygen to water, but it works with fish tanks that hold only a small amount of fish in many liters of water. A far more effective way to charge water with oxygen is to spray the water through the air, which many hydroponics growers do to supply their rapidly growing plants with the large amount of oxygen they need to remain healthy. (from "The Best of Maximum Yield" p. 26-27)
