How does co2 effect Ph?

[coach_z]

i was looking up some information about co2 kits and they were talking about ph regulators hooking up to the co2 unit for a 'fully automated' unit.

can someone help explain to me how co2 levels effect ph and vice versa?

thanks!

-chirs

 

[A. Nonymous]

CO2 in the water forms carbonic acid. Acid of course lowers the PH.

 

[vequalsir]

CO2 will decrease the ph of your tank (make it moe acidic). This counter acted by the buffering ability of your water (KH). This relation is how a co2 drop checker works.

If you are looking into moving to a high or low tech CO2 system, invest in a KH test kit or a drop checker.

 

[Amphiprion]

CO2 in the water forms carbonic acid. Acid of course lowers the PH.

Right.

CO2 + H20 --> H2CO3

This then dissociates readily into:

HCO3- + H+

That dissociated hydrogen ion is what technically increases the H+ concentration and therefore lowers pH.

This is a spontaneous reaction that occurs when CO2 is in contact with water. It is also reversible and both reactions depend immediately on the concentration of CO2 either in the atmosphere or going into the tank--less CO2 and the reaction goes in the opposite direction and you lose CO2 (not counting biological reactions that would utilize CO2).

 

[Squawkbert]

http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

^ this spells it out, but only to the extent that your tank's buffering capacity is dominated by the KH.