Drop in pH..but good growth...????

Hi all. I'm about 3 weeks into vegging and my girls look great. Lush and healthy. I've been experiencing slight drops in pH like from 6.0 to 5.7 or 5.7 to 5.5 during the light cycle. I'm not sure what it means or if it's fine or what.

TDS at the last rez change (5 days ago) was about 1700 with all nutes and supplements combined. The plants took very well to it. TDS today is 1370 so the plants are using up the nutes. Usually when plants use nutes the pH tends to increase a bit, not decrease, or so I have read.

I have a feeling the plants are almost "self-adjusting" themselves to their desired pH level. I am going to ask the seed breeder what he thinks.

What do you guys think? Is it cause for concern?

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Originally Posted by Passage to Indica

Hi all. I'm about 3 weeks into vegging and my girls look great. Lush and healthy. I've been experiencing slight drops in pH like from 6.0 to 5.7 or 5.7 to 5.5 during the light cycle. I'm not sure what it means or if it's fine or what.

TDS at the last rez change (5 days ago) was about 1700 with all nutes and supplements combined. The plants took very well to it. TDS today is 1370 so the plants are using up the nutes. Usually when plants use nutes the pH tends to increase a bit, not decrease, or so I have read.

I have a feeling the plants are almost "self-adjusting" themselves to their desired pH level. I am going to ask the seed breeder what he thinks.

What do you guys think? Is it cause for concern?

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Two things. First, 5.5 and 5.8 are all within the desired hydro pH level, everyone has their own reasons and Im sure some plants like different things. That being said, pH that is constantly moving up and down will not treat the plants as best as having something more solid. Can you use a larger reservoir? Can you find water that starts out with a better pH? What are you pHing the water with? Are you pHing down or up? The down turned leaves looks to me like too high or too low of pH or high rez temps. 6.0 pH is too high. I let mine float around 5.7-5.8, but then again its easier for me with a larger rez.

I've had an issue with having to PH up all of the time. I use RO water and was using GH's PH Up a few times per day. I finally tried a tiny bit of baking soda disolved in water and used that, and my PH has been far more stable since using it.
Results could vary obviously, and it's not generally recommended over the store bought ph up. But the baking soda also helps buffer the ph, so it's worth trying anyway to see if you can go longer between adjustments.

Mr E, I switched my plants over to bloom about 2 weeks ago and finally noticed (several grows in) that the ph level in blooming nutes lean very strongly downward. I had been having the same issue you had recently...was using baking soda to keep it up but it would drop overnight which it NEVER did with the grow nutes. Guess I have been paying more attention since my molasses party. I'm now almost 3 weeks in 12/12 and am noticing the plants are now big enough to start shift the ph back upward. I'm convinced it's something in the difference between the grow and bloom nutes.

Hm I dont know. I'd been on grow nutes when it first happened to me. But could be though. PH can be a little hard to nail down I guess, so many variables, but it's important. This has been my first hydro grow, so steep learning curve for sure.

As it is now, I know I might need to up it 1 10th each morning, at the very most. And that seems pretty good so I'm not fooling with methods until next time.

not much to report today although last night the pH dropped again from 5.5 to 5.3. I thought It would level out around 5.5 but it continued to drop so I added some pH up to bring it back up to 5.9. Rez change tommorow......switching to 12/12. I think I will use a slightly weaker nute nute mix to see what the pH does. Target TDS with supplements....1500

This is a really good article on water chemistry that talks about PH buffers and much more: International Cannagraphic Magazine Forums - BigTokes ~ Basic Water Chemistry!!

I have noticed PH tends to start to drop as the rez hits about day 7 or 8 and the plant has spit some waste back into it. Im not sure if i'm right though on my reasoning. Anyone?

I don't know either, I sure would like to know. Maybe Zandor can chime in on this common question.

You know I honestly never have had the problem until this grow and it definitely happened as soon as I switched to bloom nutes.....I kept my plants on grow for the first week of 12/12 at Zandor's and lw's suggestion so I know it wasn't the lighting......definitely the nutes and since the plants have grown like beasts I am starting to see the shift back to the ph rising slowly. I don't think it has anything to do with how old the solution is because it seems to happen even with a fresh res change. I agree with Mr E that small amounts of baking soda seem work better keeping the ph up than the normal ph up seems to.