Path: utzoo!hoptoad!amdcad!pyramid!decwrl!ucbvax!agate!ig!uwmcsd1!bbn!husc6!yale!Ram-Ashwin
From: Ram-Ashwin@cs.yale.edu (Ashwin Ram)
Newsgroups: alt.aquaria
Subject: Re: potash & PH
Keywords: ammonia
Message-ID: <23050@yale-celray.yale.UUCP>
Date: 12 Feb 88 19:39:48 GMT
References: <2627@encore.UUCP> <4767@ihlpg.ATT.COM>
Sender: root@yale.UUCP
Reply-To: Ram-Ashwin@cs.yale.edu (Ashwin Ram)
Organization: Computer Science, Yale University, New Haven, CT 06520-2158
Lines: 28
In-reply-to: dalka@ihlpg.ATT.COM (Ken Dalka)

In article <4767@ihlpg.ATT.COM>, dalka@ihlpg (Ken Dalka) writes:
> >My question is:  will high PH encourage ammonia or algae buildup?
> 
> No. However High PH makes ammonia more deadly. That is, the same
> ammonia concentration at higher PHs is more deadly to fish than
> at lower PHs.

Ken is right.  Ammonia exists in water in two forms: as free ammonia (NH3),
a gas that is highly soluble in water, and as ammonium ions (NH4+).  When pH
rises (more OH- ions), some of the ammonium ions get converted back into
free ammonia (which doesn't escape because it's so soluble).  Free ammonia
gas dissolved in water is one of the surest ways of killing fish.  NH4+ is
bad too, but to a far lesser extent.

This is why you can kill fish by raising the pH without increasing the
"amount" of ammonia, since it's the free ammonia content that really counts.
If your tap water is slightly alkaline, doing a partial water change in an
acidic tank with too much ammonium in it can actually hurt.  This is the
reason behind the popular myth that you should save every bit of "old" water
when you take it out to clean it, and then put it back in.  If you have the
ammonia buildup under control (as you should once the ecosystem is stable),
there is of course no reason to do recycle old water.

-- Ashwin Ram --

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