I just finished a couple of days of blackout in my 55gal community planted tank to try to get a cyanobacteria bloom under control. It seems to have worked fairly well, but by dedution, it seems like my phosphates are too high for the nitrate levels in the tank.

I can't find a LFS who sells a phosphate test, so I'm inferring that that's the issue. My Nitrate levels read at almost zero, so my question is:

Does anyone use salt peter (Kno3) as a water conditioner, or is there other stuff in there that might do harm?

I generally like to try to be hands off on the water chem. side of things, but I equally don't like spending two hours a week pulling black gunk out of the tank.

KNO3 is one of the chemicals used by "high tech" plant people to mix up their fertilizer doses. The key to suppressing any algae, or even cyanobacteria, is vigorous plant growth. That by itself will reduce any form of algae competition.

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Fishless cycling

Thanks, I just wanted to make sure there wouldn't be any nasty side effects from not using a canned, 'buy it in the bottle' fertilizer.

From my reading, and the tests that I have, I'm guessing that I have an excess of phosphates (which cyanobacteria utilize easier than larger plants) and not enough Nitrogen for the larger plants to take advantage of it first.

Hopefully I can do a couple of doses, get things back into balence and let the plants keep the tank under control as they should.