pH keeps crashing!

Maybe someone can help me out as I have no clue what is causing this. Every day I fix my pH to between 5.8 - 6.3, the next day it always reads around 5 or even less every damn day for the past month.

Currently plant is on bloom phase (2 months old), been growing consistently without issues or signs of anything really, however I really want to understand why this is happening.

The only thing that keeps the pH stable is when I add bicarbonate of soda.

Below are some things might that might be helpful -

Strain - Golden Leaf (not auto) (ILGM)
GHE trio nutes with calmag as extra and voodoo juice at the moment
Ro water with around 100ppm to start (have to change the filters)
TDS currently on 1200 - 1300 ppm
Lightsx2 900w Kingbo Dual optical 60cm away
Temperature and humidity as per photo
Extractor running as per light schedule 12 hours on 12 hours off
Water temp set at 18c constantly

Solutions I tried - change water completely, reduce nutrients, reduce air pump flow, add tap water (extremely bad in my country running 1000ppm out of the tap so try to avoid as much as possible)

Thanks boys for any help!

Have you tried using the tap water to see how stable it is?

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Yes at one point even around 25 - 50% tap I added to see if it will stabilize however still the same kept on crashing

The additional minerals do help stabilize the ph. I know hydro wanders in ph, I’m just not certain how long it takes, or how long it should stay.

I don’t see H2O2 in your SOP. How are you keeping the reservoir sterile(ish)?

Stop using this: it’s harmful to the plant in long term. Not sure how much in hydro but soil can be a problem.

I had huge PH issues using GH but ONE component–cal mag–was FF. That turned out to be the culprit. Best to stick with the same maker/brand of components when possible. GH is buffered for R/O too so good choice.

How big is your bucket? This will cause issues with a small reservoir size. You may have to introduce a rez or increase bucket size ( I use an 18 gallon tote per plant).

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Really want to stop using the soda, only twice I added a tablespoon so no damage done (hopefully)

Currently using a 62 liter bucket, but I fill it up to 45liters as there are pipe on the side and it starts to leak or overfill to the rockwool

Is there a particular brand you would suggest for growing? Always used GHE Trio as main nutes. These is all I use (currently using the trio, sensei cal mag and voodoo juice) Bought the ghe calmag just to start using only one brand. Would you recommend I use it with the trio?


I use the same GH base nutes along with the supplemental line. The rule of thumb would be no mixing brands. Especially cal mag. I had issues with FF cal mag in GH nutes–foaming and unreliable PH. Changed to GH cal mag and all is good.

Good sized tote: probably the best thing you can do.


Usually when I have ph drops like that I drain system wipe it down and refill with new clean water ph’d and nutes per your schedule.
This may be a root issue that can cause it. Most use damn I forget name. It’s for hydro to keep roots good.
Water temp can be a problem that causes that also if over 70f .
I use sensizyme through whole grow ro keep root zone clean. Most use error. Someone will chime in I hope.
Anyways best of luck. I would for sure drain and clean system(wipe with clean towel or paper towel) also check for clogged filters if you use a reservoir and water pump.
How do roots look ? Pics in white light would be great. Just shut off tent lights turn flash on for phone pic and poof we have perfect pics.

Hydro guard ? Maybe or something close

What is extractor that runs on and off


Running an air stone?