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Re: Ca as PO4 remover?
- To: Aquatic-Plants at actwin_com
- Subject: Re: Ca as PO4 remover?
- From: "Louis Lin" <lhclin at aw_sgi.com>
- Date: Wed, 15 Apr 1998 10:05:53 -0400
- In-Reply-To: Aquatic-Plants-Owner at actwin_com (Aquatic Plants Digest) "Aquatic Plants Digest V3 #204" (Apr 15, 3:48am)
- References: <199804150748.DAA22213 at acme_actwin.com>
> Those familiar with water treatment methods know that:
> 5 Ca + 3 HPO4 + H2O --> Ca5OH(PO4)3 + 4 H
> Hydroxyapatite (Ca5OH(PO4)3) precipitates out.
> Does anyone know the solubility of hydroxyapatite, and how
> pH-sensitive is this reaction? If it only occurs at high pH, then it
> isn't really feasible for aquarium use. Would the addition of Ca be
> as effective as a phosphate-absorbing resin?
Correct me if I am wrong, but the reaction above only happens at high
pH and probably have little use for most planted aquaria.
Using Ca to precipitates out PO4 is one of the main advantage of using
Kalkwasser (solution of calcium hydroxide) as replacement water in
marine aquariums. But that is adding a solution of pH 12 into an
aquarium with pH 8.2.