Ph fluctuation

Hey guys I noticed my ph in 24 hours went from like 6.4 to 7.2 and I really dont get how that could of happend is this normal? I’m using white vinegar to lower the ph and general hydro nutes maybe my meters fucked does anyone have a set vinegar recipe for 5 gallon bucket? Just so I can make sure its right I usually put 3 caps in


My tap water goes from 7.0 to 7.6 if left in a bucket overnight. Is it possible this is what’s happening to you?

Tap water varies so I can’t give you a rule of thumb.

I would recommend a commercial pH down. IIRC vinegar works but is not stable.

All the best


While growing in DWC I used Advanced Nutrients pH perfect so the nutes where chelated independently of the existing pH, the plant was happy and so was me, no pH pen needed … beer3|nullxnull

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What’s the starting pH of your water? If it’s much above 7, and you’re trying to get it down to 6.4, your acid might not be strong enough.

Why did you decide on vinegar?

Also a 5G res is going to swing in pH pretty frequently. The bigger your res, the more stable your pH is going to be.


I posted this on your rollitup thread, but I’ll post it here too.

Vinegar is not great at controlling PH. It doesnt last long and breaks down. Its also an organic product, and can feed/speed up bacterial growth.

Use diluted Phosphoric acid (most commercial PH Down) or sulfuric acid (regular battery acid). Sulfuric is by far the cheapest option. By the way, sulfuric is what most large commercial growers use around the world, so its perfectly safe.

PH swings can be cause by:

  1. temperature swings in the water. Colder water holds more C02, which when disolved in water becomes carbonic acid = lower PH. Warm water holds less c02 = less carbonic acid = higher PH. In my tests, with my water, 10 deg F change can cause 0.1 to 0.3 swing. Your results may be higher or lower depending on your water and nutes buffering capacity.

  2. Bacteria/algae/slime etc all drive PH up as they feed. More bad crap = faster PH rise.

  3. Roots feeding unequally - can drive it either way. the unequal feeding leaves some nutes low and other hi and it gets worse over time as you re-circulate the water and the imbalance grows. the imbalance can be caused by wrong EC levels, or out of range PH, or sick roots. PH is usually the culprit.

Check your roots, rez, etc for smell, slime, cloudy water, discoloration, etc.

By the way, roots do not turn brown from nutes. They turn brown when sick or when dying.

Also - do not use anything derived from any organic source in hydro. That includes things like vinegar, kelp, worm casings, most vitamins, amino acids, etc etc etc. If it is made from plant or animal material, do not use it.

Use pure salt based nutes only or you will just be feeding the bacteria/algae/slime.

Also, if you can, keep your water temps below 70F. Higher temps breed bacteria faster.


check out my DIY threads: PH Up, PH Down


Don’t bother with gh pH down it sucks.

Ya that’s exactly I ph it to 5…8 and one or 2 days it goes up to 7.6