Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I did a fishless cycle in a tank with new STS, and some old filters. The filters had been dry for a while, so I suspect the nitrifying bacteria (Nitrospira) was dead. I did not add any source of bacteria, all the right microorganisms will find the tank even if you do not add them.
If you want to jump start the cycle, the look for a product that specifies it contains Nitrospira species of bacteria. Do not waste your money on anything else.
STS removes the KH from the water, and these bacteria use the carbon from that source, so I kept adding baking soda to keep the KH at least 2 German degrees of hardness.
The fishless cycle went pretty normally, too 3 weeks.