What Causes Ph to Drop?

Although... shit, I let the water level drop more than I wanted to and it;s been five days since I last used chloramine... I re dosed it today but could there be bacteria in my reservoir that's causing pH drops?

I get that pH drop on certain strains.

Im 47 days from flip and still getting rises and feeding 1.5EC still. Set pH to 5.6 and 3 days later when its time for a new res(I don't top up, I let the water level drop low and just dispose of the remaining water) the ppm is about the same and pH is around 6.3

I use a lot more of the 5-11-26 mix now than I did before and getting much better results and more stable pH. I use it 4:1 in flower to CaNO3. 3:1 in veg. No more dark green leaves and ramshorning. I do 0.8EC of 5-11-26. 0.2EC of CaNO3. 0.16EC of MgSO4. 0.16EC of MKP. Tap is 0.16EC so that works out to about 1.5EC.

What I see happening now is there is a point when the water gets too low that the pH drops and feed increases. I think its used everything it needs out of it and the remaining solution is filled with nutrients it doesn't need as much of and the plant is still drinking so that causes the pH to drop and EC to rise.

I'm on my first hydro run, so I didn;t know what to expect. I noticed that the leaves are getting a bit burnt... funny thing is that I didn;t change the feeding schedule and the ppms are stable throught the week. I'll lower the ppms, she's probably not that hungry anymore!

Same shit is happening to me... Right around the start of week 4 of flower (day 22-24) the ph will drop from 6.0 to 5.0 over night. I run DWC and it just starting happening all of a sudden with a few of my plants at week 4. What is the solution for this???? Also plants were NOT showing any signs of deficiencies, buds look normal and large... Also someone said City's usually change there City's water make-up especially in the spring. Maybe just wait it out if this is the scenario ??

Thanks expert help would be appreciated.

It sounds like a lot of issues being described may be related to how the water is being buffered. I read a really good article talking about the ion exchange, I'll try to find it.

303 said:

I'm having the same problem, although my ppm's are around 680-720. Ph starts at 5.8, wake up in the morning and its at 4.1. ppms drop very very slightly. But this is reoccurring everyday and I can't figure it out. Maybe as said in the above quote salt build up? My water is super hard (210ppm). I have been using h202 thinking bacteria maybe the culprit, but hasn't changed anything. I'm also running 1500 ppms co2, I've read somewhere it can drop into your res's and drop the ph? Any thoughts? I'm week 4 flower, recirculating hydro.

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Same issue, shut down Co2, reschange out, dropped ppm. Same shit different day lol. I don't think it's co2. I'm thinking too much N. I've rent the same res water for nearly three months with Co2 and no issues then like turning on a switch ph starts bottoming out. I'm gonna try cutting way down on N next. Let me know if you find a solution and I'll do the same.

My420 said:

No you are ok. It is natural for the PH to rise usually untill about week 4-5 in flowering then the PH starts to drop. Nothing to worry about that means that everything is ok. Just stay on top of your PH and dont let it get out of line. I have to adjust mine to raise it every time in that stage of flowering.

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I've been having this same issue.

Thought it was the algae. Thought it could be a pathogen. Thought it could be root rot. Thought it could be EC too high.

I had no pathogens or root rot so those were instantly eliminated as potential causes.

I did have pretty bad algae blooms. So I went to work eliminating the algae. Which I've done. And yet the pH dropped still around week 4-5.

So I lower the EC from 1.8 .... then again on the next run to 1.6 .... then again on the next run to 1.4 .... all the while the plants were never showing any signs of burning or nute lockout. But I had to make sure the EC wasnt the problem.

From what you're saying is that unless I actually see any signs of nute lockout (ie burning or deficiency discoloring) that I can safely assume there hasnt been any lockout. That the pH dropping is totally normal? Just add fresh water until the pH rises back up? Add nutes as well or let the solution dilute until the next flush? I got things at 1.4 right now, which just seems really low but Im also running a recirculatory system so they typically dont need real high EC's.

blackforest said:

Same thing happens to me in all my hydro cycles. I'm in week 5ish and yep, the PH drops. Before this point, it would always rise. It kept happening regardless of what I did to my system, so now I just expect it. When it gets to this point, I basically keep my top off rez at 7+ ph and more or less it helps keep the ph in the system constant. At this point, I will also bring my ec down to about 1.0, they seem to like it better at this stage in flowering.

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Did you ever figure out what the problem was?

Were you ever seeing a plateau in your bud/cola development during this period?

Old thread I know but I am always getting PH drop at weeks 4-5. It doesn't seem to go below 5.5 but can drop to that from 5,8 overnight. I have been adjusting it back up every day but wonder if I should just leave it be unless it goes below 5.5?

I am feeding at 1.8ec and change out every 2 weeks or when the plants have consumed the rez volume whatever comes first.

The ph drop does seem to coincide with the EC increase from 1.6 to 1.8. My ec stays stable and plants look great.

U change the rez about every two weeks fartoblue? U ever notice around day 10 that the ph of youre DWC rez doesn't like to go below 6.1 even when u add ph down. I wonder why?

Meast21 said:

U change the rez about every two weeks fartoblue? U ever notice around day 10 that the ph of youre DWC rez doesn't like to go below 6.1 even when u add ph down. I wonder why?

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By day 10, are you referring to day 10 of flower or day 10 after rez change. Must admit if I add PH down it will always go down.

I used to get massive PH swinmgs down when i ran a DIY RDWC when i was over mid way through flower. I was flooming the pots and had air stones in the res.

I googled high and low. No root rot, plenty of dissolved oxygen, even explored the theory of too much Co2 getting into my water through airstones etc.

Then someone on another forum mentioned the exchange of ions and the plants needs at that time of bloom. I cant find the post but it summed a few things up, and I cant remember a lot of it, and it was over the top of my head, but he mentioned something about the way Potassium and other salts exchange ions when consumed. Potassium is a + ion and when consumed it creates a -ion hence the ph down. There was a way to balance it out but im stoned too much to remember, and there were other things involved like the type of salts used in the nutrients being used. It basically summed it up to the plants eat a lot of one salt or another and it was unbalancing the solution causing massive drifts.

If youve got no slime, plenty of D.O and theyre eating and drinking, figure out what other mineral the potassium exchanges ions with.

*shrugs* I just used lots of silica to ph up instead of PH up till it stopped. Think the solution needs buffering with summat

Bro science at its finest lol

I FOUND IT

Quoted from elsewhere

" As plants remove nutrient ions from the solution, the solution’s pH drifts up or down. If left uncontrolled, the pH will often drift downwards for several days after planting a new crop, after which the pH will steadily increase.

This is due to the differential uptake of ions from the solution, with the release of hydrogen (H+) or hydroxyl (OH-) ions from the root system.

As positive ions such as cations Ca2+, K+, Mg2+ are removed from the solution, hydrogen ions (H+) are released from the root system to equalize the ratio of anions to cations in the root zone and this lowers the pH of the solution.

When the crop begins an active growth phase, anions such as NO3 are taken up, which increases the pH through the release of hydroxyl ions (OH-) into solution.

Once plants are well established, most hydroponic systems tend to see a gradual and continual increase in pH over time, which is countered with doses of diluted acid. "

READ ME - https://manicbotanix.com/ph-in-hydroponics/