Does co2 change the PH?

[Mgamer20o0]

I thought I read some where when you add co2 the ph changes. I can’t find where I found it so I am no 100% sure anymore. If it does change, what is the best way to get the ph back down? I am still trying to understand all this, but I am getting close.

thanks for all your help

[CHINABOY1021]

co2 injection will bring PH down.

[carpguy]

CO2 is carbonic acid -- adding it will lower your pH.

The relationship between pH and KH can be used to measure the CO2 level (http://www.sfbaaps.com/reference/table_01.shtml) in your water. (The light area on the chart is suboptimal for plants, the middle band is ideal, the dark area is getting too high for the fish to be comfortable).

If you have a very low KH, adding CO2 can cause a pH crash. Supplementing your KH with crushed coral or baking soda is a good idea if your KH is lower than 3 dKH.