Originally Posted by Sageo3000
the ppm is almost back to zero. I haven't checked the nitrogen levels. I will do that when i get home. Should the nitirites and nitrates be at 0 also>? haven't lost any fish yet.
The nitrite will rise and then fall back to zero as the second part of the nitrogen cycle once the ammonia is at "0" or nearly so. When the ammonia and nitrite both read "0' it means the nitrosomonas and nitrobacter bacteria respectively have multiplied to the level that can handle the ammonia and nitrite being produced by the fish/nitrogen cycle. When you consistently have readings of "0" for ammonia and nitrite for several consecutive days, the tank is cycled for what's in it. Once a tank is cycled and this biological equilibrium is established, the ammonia and nitrite should always read "0" and will only do otherwise if something occurs to make the system crash biologically (things like adding too many new fish at one time, destroying the bacteria by cleaning the filter and gravel at the same time, etc.
Nitrate is a different (third) part of the process. I have never heard of a tank with "0" nitrate, but I'm not a biologist so I don't know if such is possible. But I doubt it very much. We all do weekly partial water changes primarily to remove nitrate, but also to replenish minerals and trace elements that the fish (and plants in a planted aquarium) require, as well of course as simply removing foul water and replacing it with fresh. Nitrate is basically harmless to the fish, unless the level rises. Different fish have different tolerance levels for nitrate, but most authorities recommend keeping the nitrate below 40 ppm and preferably under 20 ppm. The nitrate in my two aquaria is constant at 5-10 ppm, due to the fact that I do weekly partial water changes of 40-50% and the tanks are fairly heavily planted and plants use nitrate.
I'm glad to hear you've had no fish loss so far, which makes we wonder if the pH in the tank is acidic (under pH 7.0 which as you probably know is neutral)? Have you tested it, and if so could you post the reading?