Originally Posted by
DJW
I have tested some of these cycle starter products in carefully controlled conditions, and they don't work very well. The best way I have found to start a cycle, if you don't have some live filter media or don't want the risk, is to use a handful of soil from the garden. It has everything you need and its dirt cheap. Nitrifying bacteria live in soil; they don't do well stored in bottles.
Bottled bacteria is a complicated subject. I could post the experiments and results, but the overall conclusion is they don't have what you need and when they seem to work its because the tank would have cycled anyway, from nitrifiers entering the tank incidentally.
If you want to try the soil method, get soil from the same kind of place you would dig for earthworms. Take soil from the top inch of soil in a place where there is some dampness (but not adjacent to an aquatic environment), and where leaves or other plant litter is decomposing. Put some in a jar with water and shake it good. Let settle for a few seconds and pour most of it in the tank. It will be cloudy at first. Every time I have tried this in a sterile tank I had a full cycle in about a week. You still need to feed ammonia to build the bacteria up to match the expected bioload.