"Add Homonym" wrote in message ...
What I don't get is this: It was explained to me that the problem with
intense biological filtration is that it works to well, hence the
nitrate buildup. That makes sense. But if you slow things down, relying
only on live rock and sand for the first two stages, so that the
anaeobic bacteria in the sand and rock can keep up with killing the
nitrates, why do you not see at least a slight rise in ammonia and or
nitrites?

Let me try... When you add a canister filter, sponge or any other
mechanical filtration to your tank you are catching organic debris
in the mechanical media and it accumulates there. Plankton,
pieces of live algae, amphipods... they get trapped in the sponge
and they die there. If you keep your mechanical filter clean, let's
say clean your sponges every day - than you should not see the
problem... But who could be disciplined to do it ? :-)
So the fact is that this sponge or canister is left for weeks or
months with this organic matter trapped there, rotting and turning
into nitrates very efficiently. In most cases it is EXTRA material
which would be normally living tissue in the tank (plankton) or
got eaten by some animal (amphipod or worm in your sand).

Now - anaerobic conversion has quite small capacity - it cannot
deal efficiently with increased load. Aerobic conversion, turning
ammonia into nitrates is quite opposite: as long as you provide
nice water flow and water contains oxygen than with more food
you will quickly have more nitrating bacteria, quickly overwhelming
anaerobic counterparts and destroying previous ballance with them.

So adding mechanical filtration and not cleaning it at least every
day not only improves aerobic conversion, but also ADDS amount
of the organic gunk bacteria is feeding on by converting living
tisue or detritus which could be eaten by worms in your tank with
food for your aerobic bacteria.

This is how I understand the process...
But I am not a marine ecologist so I might be very wrong here :-)