> Help. Where does ammonium come from? I thought ammonia was what the fish
> secrete. If so, something must first turn ammonia into ammonium ... Where
> does that something come from? TIA.
The ammonium ion NH4+ is relatively harmless nitrogen compound. However,
depending on the pH value , a part of it changes into ammonia NH3. Ammonia is a
toxic gas, which can penetrate the cell walls in the same way as oxigen or
carbon dioxide. The proportion of ammonia in the water increases in line with
the pH value. If the pH value decreases, the ammonia changes back into harmless
ammonium. This process takes place spontaneously without any involvement of
bacteria, and can be repeated at will over and over again. If the pH value is
less than 7 the amount of toxic ammonia is so negligible that it can never
become a problem. By the way the temperature also plays an important part in
> A related question: when one has a biofilter in a heavily planted tank,
> would the bacteria and the plants be in competition?
Very good point. That is in fact the case.
> If so, who gets what
> first? My guess is the filter gets the ammonia first because it's puming
> the water through while the plants stand around waiting. Thus, the plants
> are more likely to get only nitrates--which we now know they have a harder
> time making use of.
Most of the filters on the market work only oxidatively (mechanically = aerobic
nitrification). The only filter available (that I am aware of ) on the market
that works reductively (bacteriologically = anaerobic denitrification) is made
by Dennerle. Unfortunately it is available only in Europe. Come to think of it
I have come accross the one made in North America ? but I don't know the name
Franc Gorenc franc at golden_net
Kitchener, Ontario http://www.golden.net/~franc