Re: Problems with DIY CO2

> From: Stephen.Pushak at saudan_HAC.COM
> I have a question: when is it appropriate to use calcium carbonate
> instead of or in addition to sodium bicarbonate? How much should be
> used and is it used up? Your helpful advice is appreciated. ;-)

Sodium bicarb will increse the KH (acid buffering, alkalinity) and add
some sodium ions to the water. Calcium carbonate will raise both KH
(via the CO3) AND the GH (general, calcium hardness).  Which one or
what kind of mix depends on your tap water and desired aquarium KH and

One teaspoon (about 6 grams) of sodium bicarbonate (NaHCO3) per 50
liters of water will increase KH by 4 degrees and will not increase
general hardness.  Two teaspoons (about 4 grams) of calcium carbonate
(CaCO3) per 50 liters of water will increase both KH and GH by 4
degrees.  Different proportions of each can be used to get the correct
KH/GH balance dictated by the fish and plants in the tank.  Since it
is difficult to accurately measure small quantities of dry chemicals
at home, a test kit should be used to verify the actual KH and GH that
is achieved.