"blank" wrote in message . au...
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).

Non CO2 tanks don't benefit from adding KNO3 generally if you are
setting it up as a planted tank.

The balance is much easier to maintain in the long term by adding more
fish food/fish/algae eaters.

That is your source of nutrients, not inorganic components. Many
people will tell you to add this or that, and that's fine, for a CO2
enriched tank, but non CO2 tanks are Carbon limited and sometimes co
limited but low NO3/PO4 etc at low CO2 levels does not affect things
as bad as when you have the high growth rates associatred with the CO2
enrichment.

So stop being so damn obsessive, add more plants, or let these grow in
more and feed your fish more as the plant biomass increases.
Try Hemianthus, pearl grass for a foreground plant.

I would not trust the cheap test kits unless they have been gauged
with a known standard. NO3 readings are notoriously poor with most
test kits.

Make clear when asking for help, that you are not using CO2.
If you have a light fish load etc, then adding KNO3 maybe appropriate
but generally adding more fish and fish food is better.

See Diana Walstad's book and some various sites on non CO2 methods. I
have fully planted very nice looking tanks that have never had CO2 or
a water change done in 6+ months.


Regards,
Tom Barr