DWC water not going down but plant roots still grow

littlegrow · Jun 11, 2017

Hey guys just wanted some info i currently have a single plant in a 5 gallon DWC the plant is growing fine apart from on the cotyledons one is starting to turn yellow but the plant is continuing to grow nicely

the PPM is not going down nor is the water level but the roots continue to grow like mad. and so does this plant what does this mean ?

i let the ph drift to 5.3 - 6.5
ppm is 300ppm
room temp is 22 degrees
humidity is between 45 - 70

Speed of green · Jun 13, 2017

What is the time elapsed that you haven't seen any changes in the ppm or water level?

what is the size of your reservoir?

it sounds like you have a small seedling and a large rdwc system, it will take some time for the small plant to consume the water and nutrients at a noticeable rate.

also your meter may not read ppm in tenths, mine goes up by 100's

Dro Smoe · Jun 15, 2017

littlegrow said:
Hey guys just wanted some info i currently have a single plant in a 5 gallon DWC the plant is growing fine apart from on the cotyledons one is starting to turn yellow but the plant is continuing to grow nicely

the PPM is not going down nor is the water level but the roots continue to grow like mad. and so does this plant what does this mean ?

i let the ph drift to 5.3 - 6.5
ppm is 300ppm
room temp is 22 degrees
humidity is between 45 - 70

It's normal for the cotyledons to yellow as the plant matures and pulls nutrients from them. It means that you're in my favorite stage, the stable and easy beginning. They'll grow strong in the early stages of veg, and nute strength will remain stable, as well as PH and water level. In no time you'll be rising so just keep an eye on it - once a day is plenty. In early-mid flower you'll be fighting to keep the PH up, although some strains are much worse than others.

You'll start getting crazy swings if your reservoirs are dirty (decaying organic matter - sloughed off root cells), so do a res change at least once every two weeks in early-mid veg, and once a week from late veg on... Although I'm guilty of slacking once in a while and skipping a week so long as they're happy - they'll let you know.

Dro Smoe · Jun 15, 2017

Also..

6.5 is too high.. Try not to go above 6.2.. 5.2-6.2 is acceptable, with 5.8 being ideal. You'll find that topping with PH'd nutrient solution will get you much further between res changes. Just base the strength of your top off on what the reservoir is telling you.. If it's say 6.2, 900 ppm (0.5 conversion meter) and you want to bring PH and EC down, make something like 5.2-5.4, 400 ppm.

Douglas.Curtis · Jun 15, 2017

Plant is too small to use enough water/nutes to have much of a change going on.

Perfect pH in DWC is a slow rise from 5.4 up to 5.8 and then nutes being added to drop it back to 5.4 again. This is a natural pH swing which will happen as the plants eat nutrients. Since plants are small, the res size should be small as well. Keeping a steady pH with DWC grows sub-par cannabis.

Ph dropping is from root rot. Root rot is easy to have happen when the nutrient strength is too high or the nutrient temp is too high. Temps need to stay between 65F and 69F, for best results and minimal chances of root rot. Do a search for "Ask Lucas" and read the thread a few dozen times, the res management methods are just as important as the nutrient mix profile you're using.

Welcome to the wild, wild, world of cannabis cultivation.

Dro Smoe · Jun 15, 2017

Yes but root rot is not the only cause of PH drops so don't be alarmed when it happens.

There are a few reasons:
A plant that is taking in more water than nutrients (solution's too strong) will cause the solution to concentrate, subsuqently raising EC and lowering PH; signs of burn may or may not accompany (burnt tips/leaf edges). The stage of growth comes into play as well because when the plant is flowering it'll be taking up more Potassium, and therefore exchanging Hydrogen which will cause PH to drop. Also as I mentioned, organic decay of any kind whether it's decaying root material floating around your buckets or root rot,
will cause drops..

Douglas.Curtis · Jun 15, 2017

Yeah... about that, you might want to do more research. In the last 15 years running DWC, I've never had pH drop for reasons other than root rot. I've definitely had root rot for a variety of reasons, namely too much heat or too hot of nutrients. Both of which will cause root rot and drop the pH. The plant isn't taking in more water than nutes, the roots are being damaged and rotting.

I mix my res and use the same nutrient solution throughout flower, only topping off with pure r/o and using nutes as pH down. Shouldn't be any organics floating in your res, it should be nice and clean at harvest time.

Absorbing potassium dropping pH? Yeah... you might want to back off the nutes going into flower. Use a balanced nutrient profile, keep the strength below maximum for the strain/pheno and watch your temps. When that's all in check, your pH will always go up over time, regardless of whether you're in veg or flower.

Dro Smoe, I suggest you go find the "Ask Lucas" thread as well because you'll thank yourself with the reduced effort and increased results. Hydro is super simple, when you fully understand what's going on.

Dro Smoe · Jun 15, 2017

As roots grow they slough off cells, that is basic plant biology, friend. 68-70F reservoirs and nutrient strength below 1000ppm do not damage roots, not sure what would bring you to that assumption..?

I too use an ro (3ppm) base, and a balanced one-part Nutrient (Ionic) that I don't take above 1000ppm. I'm yielding 8-10ozs per plant and have been for 6+ years (14 on and off). You'll see below a rootball below from THC Bomb - a 10 oz plant which liked to pull PH down. I'd be interested to see you point out the rot...

Douglas.Curtis · Jun 15, 2017

I'll go out on a limb and say the pH dropped after approximately 30 days or so in flower. Correct?

Dro Smoe · Jun 15, 2017

I'd have to take a look at my journal when I get home, but if memory serves me (two years ago), I believe it was closer to 50 or so.. I feel that we're taking away from the OP, but feel free to PM me if you'd like to discuss it further =)

packratt · Jun 15, 2017

Excellent info Dro Smoe. All of it is bang on. Thank you for posting that.

Dro Smoe · Jun 15, 2017

packratt said:
Excellent info Dro Smoe. All of it is bang on. Thank you for posting that.

My pleasure, hope it helps you out. :plant grow:

Douglas.Curtis · Jun 15, 2017

Dro Smoe said:
I'd have to take a look at my journal when I get home, but if memory serves me (two years ago), I believe it was closer to 50 or so.. I feel that we're taking away from the OP, but feel free to PM me if you'd like to discuss it further =)

On the contrary, this is excellent information for new growers, especially with DWC.

When you check your notes, you'll see the strain was longer than a 60 day strain. When the major growth of flowers slows, so does the high demand for nutes. The nutrient mix was too hot for the reduced need for nutrients at that time and your pH dropped from the beginning of root rot.

Did it a few times myself. Perfectly natural when your mix is bordering on too hot as it enters that stage of flower.

Dro Smoe · Jun 16, 2017

Douglas.Curtis said:
On the contrary, this is excellent information for new growers, especially with DWC.

When you check your notes, you'll see the strain was longer than a 60 day strain. When the major growth of flowers slows, so does the high demand for nutes. The nutrient mix was too hot for the reduced need for nutrients at that time and your pH dropped from the beginning of root rot.

Did it a few times myself. Perfectly natural when your mix is bordering on too hot as it enters that stage of flower.

I respectfully disagree. You're attempting to diagnose a major root pathogen, without even knowing basic information such as: water temperature, EC, environmental conditions etc.. And after seeing a picture of the plant's extremely healthy root mass at harvest nonetheless .. I don't see how that benefits the OP.

To clear up the misdiagnosis that you're providing I'll supply the details, but won't discuss it any further out of respect to the OP:
Res temp - 67-68F.
First PH drop (4 points) 42 days
EC - 750ppm (0.5 conversion) and stable
76F Day Temp / 63F Night Temp
20-25% RH
Roots robust and creamy white (slightly stained due to color of Ionic nutrient)

When I have issues with PH drop I simply add back a little dechlorinated tap to my top off to bring them back up without using PH up (will cause salt buildups and lockouts if abused); or I use the alkalinity of Ionic's PK boost to my advantage and add it to my solution (very seldom, and only if I need to increase EC as well).

While a forum is not empirically based, do yourself a solid Douglas and follow this thread search on PH drop.. You'll find a plethora of explanations in agreement with mine.

https://www.icmag.com/modules/Find_Threads/index.php?stext=PH+DROP
https://www.icmag.com/ic/showthread.php?threadid=211616
https://www.icmag.com/ic/showthread.php?t=172234

https://hydroponics.com/question/my-ph-keeps-fluctuating-whats-going-on/

kickapoo · Jun 16, 2017

I really like the info on res management Dro Smoe. Exactly how I was taught long time ago, based on all the reasons you have listed.

Douglas.Curtis · Jun 16, 2017

Dro Smoe said:
While a forum is not empirically based, do yourself a solid Douglas and follow this thread search on PH drop.. You'll find a plethora of explanations in agreement with mine.

Yes, I see others agreeing with you. Yep. If that's good enough for you, carry on. I also see others stating the exact same thing I am. White roots do not mean rot is not beginning. On a side note, yellow HPS photos are not something to show others the health/color of your roots.

No worries though, you mean well. :tiphat:

Dro Smoe · Jun 16, 2017

kickapoo said:
I really like the info on res management Dro Smoe. Exactly how I was taught long time ago, based on all the reasons you have listed.

Thanks brotha :tiphat:

Douglas.Curtis · Jun 17, 2017

Hydro tip for newbies: Use r/o water as your base and top off with only pure r/o.

Why? There are three very good reasons:
1. Any correct advice posted by users of r/o can be duplicated in your own garden. Your results, in nearly the same conditions, will produce the same results. Tap/well water varies significantly in content and ph/nute reaction. Unless you're on the same water supply or have tested both sources of water to be nearly the same, your results can vary quite considerably. Variances occur from just a few miles away to seasonal, depending on your supply.

2. You want the pH rise to be natural, created by the depletion of nutrients as the plants absorb them from the solution. The rise in pH is rock solid predictable, when using r/o. What works in my DWC will work exactly the same in yours, when you use r/o and the conditions are close. This cannot be said of tap water from various sources.

3. When you start with r/o water you're only adding what the plant will use. Since cannabis is a hyper/dynamic accumulator plant, nearly anything not needed by the cannabis will also be absorbed and dealt with. These extras do not flush out and can (and often do) noticeably decrease quality of the end flower.

So, when you're sourcing information for your particular setup and conditions, be sure to check what water supply is being used. Math heads can use the tap water threads with a posted analysis (one for each major seasonal change for the area) and do the figuring against the data on the analysis of their own water.

The rest of us use r/o and look for quality info posted by other r/o growers. Removing as many variables as you can will increase your chances of success and continued improvement. Awareness is a powerful thing.

(ec stable means plants not using nutes, ie too hot and root damage is occurring, pH will begin dropping)

jedi5891 · Jul 3, 2017

WEATHER TO DO A RES CHANGE.

WEATHER TO DO A RES CHANGE.

Hey folks, ive got a DWC related query and thought id ask here if thats cool.
Im on my first DWC grow and everything is going great, massive plants with huge root balls. Ive made my own 12 pot system using 20 liter buckets each with an air stone etc. Its not recirculating, which has its pros an cons. Its handy coz its multi strain and I can cater for each plant etc.
My question is if I need to change the res when I add PK 13/14 as vita link state not to use in conjunction with Buddy, which will be in the tank before the PK booster is added.

Ive noticed how my bigger plants in the DWC are smothering the Air stones due to the amount of roots. Has anyone used a spider and if so are they worth getting. Im also thinking bigger containers as DWC is off the chart.
Peace

Douglas.Curtis · Jul 3, 2017

When mfg directions say there's a conflict, I'd follow that until I could experiment on a smaller scale.

As the root balls get larger their density increases, which can trap heat. Be extra careful to keep reservoirs below 69F, especially at peak flower. My go to stones are oxystones, new ones every run or every other run when used continuously.

I'm partial to one reservoir, per light, per strain.

DWC water not going down but plant roots still grow

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