Why does 0 PPM water p.h. go down when water is agitated

From a fellow grower: why does 0 PPM water p.h. go down when water is agitated

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Because you can not get a proper PH on 0ppm water. There is no minerals or anything in it to give a proper ph reading. It’s recommended to mix some tap water with the 0ppm water to get a ph reading and adjust. Im assuming they are using distilled or RO water. Recommended adding enough tap water to achieve 150ppm then you can PH and adjust it. If you are going to be adding nutrients to your 0ppm water then just add nutes and ph test after.


Because 0 ppm is measuring the tds (total dissolved solids) there are no tds in 0 ppm to measure when you open the water to the atmosphere it collects particles which changes the water adding tds to it


Zero PPM water cannot have a pH and it will take on the pH of the medium into which it is introduced.


‘Zero ppm water’ does have a pH. The pH change when stirring has nothing to do with total dissolved solids. It has to do with atmospheric gas.

It is important to keep mind that water (distilled, deionized, or tap) is NOT “pure” (i.e., pH equal to 7). The moment it comes in contact with air, CO2 gas begins dissolving into it, forming carbonic acid. The actual pH, therefore, will typically be slightly less than 7.

Pure distilled water should be neutral with a pH of 7, but because it absorbs carbon dioxide from the atmosphere, it’s actually slightly acidic.

When the OP stirs the water air is introduced accelerating the carbonic reaction.


Dissolved CO2 is responsible for a drop in PH of standing water, but using EC meters is impossible to get a reading under 50 ppm, per the manual supplied by the EC meter manufacturer.

You are correct that distilled water is neutral PH (7.0) but that’s no less accurate than what @ReelOfishalTrees pointed out.


I agree that EC meters used at home would make it impossible to register a pH for water with low total dissolved solids. But that’s not because the water has no pH, it’s because of the design of the meter used.

I wasn’t implying the water has no ph, was just implying with our home meters we won’t get a proper reading. Sorry if I gave wrong information. @Myfriendis410 @MH47

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I don’t think you gave wrong information. I believe using dechlorinated/dechloaramined tap is better than RO or distilled for plants because of the total dissolved solids it contains. Those TDS are the buffers (resistance) against pH changes and provide trace minerals to the plant.

Electrons are able to flow through the water from one set of electrodes to another not because of the water molecules themselves, but because of the ions dissolved in the water (aka total dissolved solids). It is these ions that transport the electrons.