On 2005-04-05, dfreas wrote:

While this is technically correct I think what Mary was refering to is
that there is more room for error in a large tank. A high nitrate level
in a large tank isn't as serious because the increased water volume is
a bit more forgiving.


I'm not sure it is... It's harder to change a larger mass, but when you
test, you're testing the average, not a one time spike. That is,
overfeeding similarly stocked 20G and 55G tanks won't change the
water parameters in the 55G as much as the 20G. But, since the units of
measurement is ppm or g/mL, then the volume has been normalized.
It's that many ppm regardless of the size of the tank.

To answer the original question, the nitrate levels depend on what
you are keeping. Some fish can stand higher levels, others can't.
Plant tanks need higher levels to feed the plants. If you don't have
plants, ideally, you probably want nitrates to be as low as possible,
10ppm or less, maybe?

My favorite trick is to use terrestrial plants to suck out the nitrates
in a tank. Devil's ivy is particularly good for this. Let the leaves
hang outside of the tank, and immerse the root and root stubs in
the water. Something else to try is to find some aquatic plants
that are nitrates sponges like anacharis, duckweed, indian fern, etc.

--
"I have to decide between two equally frightening options.
If I wanted to do that, I'd vote." --Duckman