DIY CO2 Lowering PH of tank water

[FishBen]

When I first tried DIY CO2 I noticed the PH of the tank water dived, thought it must have been caused by something else and didn't think about it again (I measured PH after adding CO2, and not before). Recently I saw on an article that claimed using a CO2 system with you tank can lower the PH of the water..

I've never seen anyone here mention it, and figured they would have if it was true.

Is this true? If it is, how do I regulate it?

[Joshlikesfish]

It is very true.

Carbon dioxide dissolves slightly in water to form a weak acid called carbonic acid, H2CO3, according to the following reaction:

CO2 + H2O --> H2CO3

After that, carbonic acid reacts slightly and reversibly in water to form a hydronium cation, H3O+, and the bicarbonate ion, HCO3-, according to the following reaction:

H2CO3 + H2O --> HCO3- + H3O+

I imagine it would be very hard to regulate with DIY, since DIY isn't reliable(lack of the right word) With a presurised system you can get a little computer that uses CO2 to keep a steady pH

[phoenix44]

you regulate it by increasing the hardness of the water slightly thus increasing its buffering ability.

A buffer resists pH change and so addition of CO2 will not decrease the pH of water as much as may have been thought.

[ryanjury]

As Phoenix suggests, increase the KH will help keep the PH more stable

[FishBen]

Thanks for the replies!

Arg!!! So much for being something simple and easy to do :lol:

So now I ask, how do I raise the hardness in the water, and will I need to continue raising it every now and then?

:oops:

[ryanjury]

Baking soda or adding something to buffer your water (coral/sea shells etc) will increase the KH of the water..

I think you need to do some reading/research to know what you are dealing with first..

http://www.cichlid-forum.com/articles/w ... mistry.php

http://www.cichlid-forum.com/articles/gh_kh_ph.php

[FishBen]

Ok, thanks! 8)

[spoon]

some people also use a powerhead on a timer that comes on when the lights are out to drive out the excess co2 as its more likely to drop the ph when the plants arent using it up i.e. at night. however this can cause more problems as the ph can swing even more and a low but stable ph is better than a quick changing ph