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Re: KH and ammonia

Steve Dixon writes:

> I'm missing something here.  Why would a rise in KH release ammonia and
>  kill your fish?  KH and pH should rise together, right?  Changing the
>  water should reduce any concentrations of ammonia, unless the new water
>  contains ammonia.  What am I missing?

Ammonia (NH3) at pH levels below 7.0 will pick up a hydrion ion and become 
ammonium (NH4+), which is much less toxic.  So a rise in KH would drive the 
pH back up over to the base side, causing the NH3/NH4 equilibrium to swing 
back, releasing the h+ ions, and becoming the nastier form.  But what I am 
missing is why water changes into a tank that is becoming more alkaline from 
its substrate would cause the ammonia release.  Should be the other way 
around in this case.

Bob Dixon