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Re: WHY Calcium carbonate as KH buffer

Chris Coleman writes:

> Currently
>  I buffer GH and KH with sodium bicarbonate (NaHCO3) for KH and
>  calcium chloride (NaCl) for GH.

Calcium Chloride is CaCl

>  Is there a reason why the CO2 posts here frequently make reference to
>  calcium carbonate (CaCO3) as a KH buffer? Is there any benefit to using
>  calcium carbonate over calcium chloride?

Using CaCO3, you can increase both GH and KH at once.  Why use two things when
you can kill two burds with one stone?
>  I prefer my current method simply because the calcium chloride effects =
>  KH
>  without effecting GH. and because it dissolves very rapidly with water.

I think you have that backwards.  The calcium chloride will increase general
hardness (total hardness) without increasing alkalinity.

Carbonate is a buffer and is therefore useful for stabilizing pH.  CO2 tends
to cause pH swings in planted tanks in keeping with the light/dark cycle.  As
to whether cabonate will help control these carbonic acid pH swings, I will
let someone more experienced give an answer.

Bob Dixon