purplekaz, it definitely should help if you do the water change. Bignose created
this thread about how water changes during a fish-in cycle don't slow the cycling process but actually speed it slightly. It was speaking of ammonia but the same applies to nitrite during a fishless cycle too. Seeing his data probably means that a fishless cycle could just as easily be done with 1 ppm per day and in less time. I may give that a try.
One thing you may try (I have done this once with success) is cut the amount of ammonia you are adding back to 2ppm once per day. That way, the bacteria are being fed and the nitrite doesn't grow to such hugh levels
Why would this matter if the tank has no fish in it? The goal here is NOT to find a way to get your test results to say there is no ammonia or nitrite present in the tank....it is to gain/grow/protect enough bacteria to take care of it all.
Of course the nitrite level is going to go down if you lower the ammonia levels.....less ammonia means less nitrite production and the nitrite that is already there is becoming nitrates at a more rapid pace than ammonia is introduced. You are only tricking yourself by doing this.
I agree with turning the temperature up...helps alot.
The cut in the amount added has nothing to do with trying to get the test results to read zero, or does it? Obviously, we don't want to get zero readings that are false and don't truly tell us that the tank is cycled but the final goal of a fishless cycle is get to the point that the bacteria can process all the ammonia and nitrite being produced, thus zero readings.
The reason for reducing the amount of ammonia being added daily is that you are cutting the amount of nitrite (via processed ammonia) you are adding to the tank daily. It takes much longer for the nitrite level to drop back to zero during a fishless cycle and I believe that is simply due to the very high level nitrite reaches, probably well over 20 ppm (I don't know for sure as my test kit won't measure over 5 ppm and I have not gone to the effort to dilute the water in an effort to get an accurate reading), during the process and not a result of nitrite oxidizing bacteria being that much slower to reproduce that those that process ammonia. I would imagine a properly stocked and fed tank of community fish (no heavy waste producers like oscar, plecs of goldfish) would produce no more than 1 ppm (if that much) of ammonia per day although I don't have data to back this up. If you take any size tank, brand new, set up properly, no seed media that contains bacteria, stock it fully, say 1" per gallon just to pick a stock level, and feed them a "normal" amount, we most likely won't see ammonia produced at a rate of over 1 ppm per day. Certainly no where near the 4 or 5 ppm per day we cycle a tank with.
Once ammonia has dropped back to zero the first time or two and the tank (filter/bacteria) is capable of processing 4 ppm of ammonia once or twice a day there is obviously plenty of bacteria present to handle all the ammonia the fish will produce. During the cycling process, as the ammonia is being added and processed, the nitrite level rises rather quickly. If we are adding 4 ppm of ammonia a day, then we are in essense are adding 4 ppm of nitrite and there isn't enough bacteria to handle that much thus the nitrite level quickly goes off the chart high and stays there for quite a while until there is finally enough bacteria to process all the nitrite. There is no way we ever need that much bacteria to process nitrite as it will never get that high from out normal fish load.
Cutting the ammonia back to 2 ppm per day, keeps the ammonia oxidizing bacteria fed (which is the only reason we are still adding ammonia as we have all the ammonia oxidizing bacteria we need) and maintains a colony large enough to handle the future fish waste while not building the nitrite to such a high level, thus shortening (probably only slightly) the time required for the bacteria to finally process all the nitrite present during the fishless cycle.
