Ph flucuation

I am using ro water and gh ph down. Put my drops in 5 gallon jug and add my air stones to get it bubbled up i take a sample and it looks right on but then come back 20 min later and its reading high again what could be causing this?

There is no buffer in ro water, wild ph swings are a possibility. Add a little calcium to it to buffer it.

Also, are you mixing the water thoroughly? Or are you just letting the bubbler mix it? If you are relying on the bubbler it may not be mixing well. And why are you bubbling the water?

Just letting the bubbler mix it. Nuets i use the calcium aka plant amp lowers ph so,u have to test before u add it

Kerovan said:

There is no buffer in ro water, wild ph swings are a possibility. Add a little calcium to it to buffer it.

Also, are you mixing the water thoroughly? Or are you just letting the bubbler mix it? If you are relying on the bubbler it may not be mixing well. And why are you bubbling the water?

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I'll use nothing but an air stone to mix a single gallon in a juice pitcher for clone trays with no problem. Each adjustment takes literally moments to level off when reading the ph with a BlueLab ph meter.

The op should buffer the water like you suggested and use a water pump in the bottom of the bucket to adgitate the mix in order to get everything to even out faster.