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Re: Aquatic Plants Digest V3 #1307


> > Interestingly, if this is right, then you can use NaOH or KOH or
> > NH4OH or any other base that strikes your fancy to raise KH without
> > raising GH (again, at the expense of CO2 levels).

> Yep.  You can do that.  The CO2 level rebounds after the reaction is
> complete.

Of course you can do all that, if your aim is _only_ to prepare water
with certain parameters, not water to keep fish in it:

If one adds NH4OH, at a pH above neutral, it is really like adding NH3
-- hardly a practice recommended for keeping healthy fish. Granted, that
with excess CO2 the pH is likely to be below neutral, but NH4+ is only
_less_ toxic than NH3, NOT inocuous.

The entire idea of having a certain carbonate hardness (KH) value is to
provide a _buffer_ that resists changes in pH. Adding NaOH to water
saturated with CO2, is like adding NaHCO3, but with the added
disadvantage of having to handle a _very_strong_ base that can easily
tip the pH to, say, 10 or 11! Adding sodium bicarbonate solution can not
raise the pH of the water above pH 8.4, unless you add more than 8.3
_grams_ of NaHCO3 per liter of aquarium water!