Let's chat about pH

Ideal range for pH in cannabis is between 5.8 and 6.8. Why is pH so important? What is with synergism vs. antagonism? Let’s chat about pH in cannabis


I would love to talk about pH.
As I understand it my ph should be gradually rising over time, but I have issues with it constantly falling. Especially in the three days following a reservoir change. I am not talking a gradual thing either. for instance, last week when i did my weekly water change, I pH’d to 6.4 because I knew it was going to fall, and 24 hours later it was down to 5.2. I will struggle for a few days to get it to stabilize, and then it will stay locked around 6.1 until I change it again. I am running a 35 gallon 12 site reservoir with 4 sites planted. I am using lotus nutrients, and hydroguard. Part of me thinks it might be the hydroguard causing the problem, so I am going to not add it this time. Thoughts?

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Oddly enough this was just a conversation on another site I follow.

As I understand it, ph allows specific nutrients to be absorbed up through the plant. Best practice is to follow the instructions on your nutrient line.

I use GH so I keep mine between 5.5 and 6.2 the best I can.



Many dwc growers experience this. Manage it as you can with pH up.

Silica can help stabilize a hydro reservoir sometimes.

Kinda sucks to do res changes sometimes if you know it’s gonna crash and I have gotten away without a res change for some time in veg but I’ve paid the price also for trying to go to long in flower

Optimal pH uptake chart for soil and hydro




Idk. What are we talking?

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the biggest problem for most growers, myself included, is to learn throwing more of an element at a plant when it’s deficient may not be the best solution, in many cases it’s soil pH or an excess of another element causing the first to not be taken up by the roots.


Thanks for including that diagram, @el_kabong! You beat me to it!


lol, knowing about Mulder’s Chart comes with great age, me, or great knowledge, gonna guess you.


I agree with @tdubwilly, Silica should be used with hydro/soiless…it is missing from those grow media but it is present in a soil grow.

there are proven benefits, it will make the plant’s cell walls stronger, the plant will be less appetizing to pests, it can help during times of high heat or low water, it aids in Nitrogen absorption…


And you! You are being highly modest today.


Silica should always be added first to the res.For stabilizing a res have you tried Z7 ? Its an emzyme that helps with that among other things…


Where you get it?


Flying Skull makes Z7 Enzyme cleanser

FlyingSkull .net


Have you checked your water level? I had al sorts of issues when I had water level touching the hydroton. I added a float valve and reservoir and been happy growing ever since. I keep water level approx 1/4” below net pot. @thepowersurge Good luck


Ph can make or break a grow. From how your medium’s pH changes over time (and why), to how nutrient uptake is affected, understanding pH really is the gatekeeper to growing the best weed.

Followed closely by VPD.


Preach it girl :smiley: Trufz


VPD seems to have increased growth rate by 1/3. Shaved serious time off my veg and flowers 5 day earlier already, badabababa I’m loving it!!! (I also started adjusting ph) so far so good, didn’t seem to work with bio canna tho.causes problems for most ppl.


Have you flushed your medium with straight water? That may help. I used to see the same thing and I used a ton of PH up. Have been using Advanced nutrients Coco line in Coco coir for a couple of years now and my wild ph swings have stopped. Still get gradual movement.

6.5 is the ideal ph for soil. 5.8 is ideal for hydro.

Oops, sorry I just noticed this has been presented.

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Hi!! If you have living soil and growing organic the PH isn’t important…
However if you are not you should aim to keep between 6-6.5 for soil!

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