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Re: Sodium bicarbonate/Sodium carbonate
- To: Aquatic-Plants at actwin_com
- Subject: Re: Sodium bicarbonate/Sodium carbonate
- From: Paul Sears <psears at nrn1_NRCan.gc.ca>
- Date: Fri, 6 Mar 1998 11:19:59 -0500 (EST)
- In-Reply-To: <199803061555.KAA07765 at acme_actwin.com> from "Aquatic Plants Digest" at Mar 6, 98 10:55:23 am
> From: Ed Hengel <hengel at computer_net>
> Subject: sodium bicarbonate/sodium carbonate
> What are the pros and cons of using sodium bicarbonate (NaHCO3) vs.
> sodium carbonate (Na2CO3) to regulate carbonate hardness? Does it
> matter one way or the other? Does either one affect the efficacy of the
Whichever you add, you will end up with bicarbonate ions in solution,
because, at the sort of pH that interests us, the ratio of HCO3- to CO3--
is large. If you use the bicarbonate, you will go directly to the new
HCO3- concentration, but if you use the carbonate, it must react with the CO2
in the water:
CO3-- + CO2 + H2O -> 2 HCO3-
If you add enough sodium carbonate to wipe out the CO2 in solution,
and do it quickly enough that more CO2 can't come in to make up, you will
get a _huge_ pH spike. It would not be at all difficult to reach pH 10.
I would use the bicarbonate.
Paul Sears Ottawa, Canada