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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
> system?
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