# Interesting find about air stones and water PH



## automatic-hydromatic (Oct 18, 2010)

Did some routine water tests today and noticed something different.

On my planted 30 gallon, I've had a steady PH of 6.6 for the past 2 months. I've also had an aerator pump with an air stone stuffed in the corner the entire time too. That is until about a week ago when I pulled it out of the 30 gallon to put in the 10 gallon Guppy raising tank that I just set up. In the week that the tank has been without an air stone, the PH has droped from 6.6 to 6.4. I know 0.2 isn't a huge number, but it just stood out to me since it's been a steady 6.6 for two months now without a single fluctuation.

I don't run CO2, but I have heard before that if you run it too much it will begin to lower your PH level. Is this the same theory with a regular aerator? Has removing it raised the CO2 level in the tank and caused the PH drop? I don't mind if that's the case really; it might actually benefit the plants in the tank. But I don't want the PH to drop too much. It's already low enough with a layer of peat moss in the substrate.


----------



## theguppyman (Jan 10, 2010)

cool observation I've never had that happen to me, but one can conclude that it might have the same effect, I really have no clue, you would have to ask a chemist he would be the one to know


----------



## JRMunroe (Feb 13, 2011)

Injecting carbon dioxide can reduce pH, combining with water to make carbonic acid.

But carbon dioxide is a trace gas that makes up only 0.039% of the air we breathe. In such low amounts, there's no way that would affect the pH. (It enters/exits the water via the water's surface just as much as it would by pumping it through the air stone.)


----------



## jrman83 (Jul 9, 2010)

The theory sounds possible since we use air stones to gas out CO2 when the levels get a little too high or at night. Injecting any amount of CO2 will drop your ph.


----------



## NeonShark666 (Dec 13, 2010)

A difference of 6.6 to 6.4 isn't enough to worry about, it's easily within the error of your measurement. If the decrease is actual it probably because some of the CO2 generated by your fish is no longer being carried out of your tank through aeriation. Water, exposed to the air, will have a lower ph than water in a sealed container because dissolved CO2 causes the ph to drop. Pure water, with no CO2 in it, should have a ph of 7.0.


----------



## snail (Aug 6, 2010)

The only think I can think is that in a heavily planted tank CO2 might be very so the air from the room actually raises CO2 levels, but I don't know if that is possible.


----------

