I have done some research and realize I was wrong regarding fish in cycling. My apologies to Byron. I was completely mixed up with fishless cycling which can still be done with Safe Start but must use ammonia. With a fish in, you will not see much ammonia and possibly not any nitrite. I haven’t done a cycle with bottled bacteria for awhile as I always seed my tanks now with used media. When looking back at my notes, it dawned on me that my cycles have been fishless ones. Again, my apologies to Byron on this one. I was completely wrong!
I am very appreciative and grateful for this post. Thank you, sincerely. We move ahead.
In subsequent posts there seems to be some confusion, as two quite different approaches are being discussed. There are two products with slightly different methods.
Dr Tim's One and Only is an instant cycling method that can be done with a few fish or as fishless cycling. There are videos by Dr. Hovanec on his website that explains this:
https://store.drtimsaquatics.com/One-Only-Nitrifying-Bacteria_c_97.html
The second product and the one originally mentioned in this thread is Tetra's
SafeStart. This is a formula developed by Dr. Hovanec and later sold to Tetra when Dr. Hovanec progressed with the
One and Only product. It is a bacterial supplement that adds live AOB and NOB and is intended for use when a few fish are added. If the fish load is minimal, and the product is used as directed, it will work to establish the bacterial colony faster because you are in effect seeding the tank with these bacteria species. Directions must be followed, but this is a safe method and with a few fish in the tank it will not cause cycling issues or harm fish. Ammonia and nitrite will never test above zero if directions are followed and the fish are not more than what the method can handle. The results will be identical to seeding your own filter bacteria. You absolutely do not add any artificial ammonia; the ammonia produced by the minimal fish load will get the cycle going.
Nitrifying bacteria (once introduced) require 12-32 hours to multiply, which they do by binary division [each bacterium divides into two bacteria].
Nitrosomonas (the AOB) multiply in less time (12+ hours) while
Nitrospira (the NOB) require more time (up to 32 hours).