DWC pH keeps dropping overnight

I couldn’t find a reply or new topic button in beginner hdro.

Using DWC. My pH keeps dropping 0.3-0.6 every night. I’ll put in pH up until it gets back to 5.8 ten it falls to 5.5-5.3 by the next day. Any ideas?

Try putting it higher. Around 6.4 and see what happens

What stage are your plants in? How big is your reservoir? What are you feeding them right now?

Can you post a picture of your setup?

I regularly see crashing PH during the transition to flower in hydro; after a couple days adjusting back to 5.8 it normally settles down. That’s in a 14ga tote that holds 8 gallons of water with 6" net pots. Smaller reservoirs will be harder to keep stable.


I’m in 5 gallon buckets. Currently 6 weeks from seed. I did 4 weeks of grow with General Hydroponics Grow 7-4-10 and am 2 weeks into flower with GH Bloom 4-8-7. I’ve been seeing the pH drops pretty much the whole time. 18 hours of light for grow and 12 for flower. I’m following Bergman’s Hydo nutrient schedule for PPM. I may have gotten the PPM too high? I saw another thread that said the pH can drop if the PPM gets too high.

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Are those 5 gal linked to a common reservoir? if so, look for a little timer battery that could have fallen in the system somewhere. It happened to me!

The nutrient numbers don’t add up to me, it appears low in potassium or inverted to the relative phosphorous.

What is your medium? Is there any organics? Or pure hydro?

If I don’t change my reservoir every week or so then my pH begins to crash

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Any number of things could cause the crashing PH.

How much water are the plants consuming per day? How much water can you put in each bucket - I’m guessing around 3 gallons? Maybe 4?

I would guess they are taking about a quart of water a day. I only use the reservoir to drain the two grow buckets. I add new water straight to the two grow buckets when I add water or change it out. I’m pure hydro.

Finally solved the dropping pH issue. Added Armour Si from General Hydroponics and its holding steady at 6.0.


Keep an eye on that - if she is growing (i.e. in transition) I have noticed crashing PH even using silica at this time - I think maybe because it uptakes the silica, removing it from the water, thereby lowering the PH?

I’ve have spent many a stoned night contemplating that one thought…

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