"blank" wrote in message
u...
Hmmm. I'm beginning to think I have misunderstood the role of nitrate
in an
established planted freshwater aquarium. My ammonia level is almost
always
zero (or so it appears from my Aquarium Pharmaceuticals test kit.) But
recently I have noticed newsgroup responses indicating that some
nitrate is
good for the plants.

Maybe my weekly 20% water change is excessive. I'd appreciate
advice--should I reduce the weekly quantity, reduce the frequency, or
just
stop being so damn obsessive? My plant growth is disappointing. The
other
paramaters are normally: pH 7.6, GH 6, KH 5, PO4 0.25. (No CO2
injection,
quite heavily stocked 75gal tank with about 25% plant cover).

If your NO3 is zero with 25% plant coverage, then you need more fish, or
to feed them more ;~) I don't get zero NO3 until I hit about 75%
coverage. I would scale back to a 10% change myself, and see if there is
a difference.

NetMax