You must have a ammonia source .
The fish is the ammonia source, you must mean nitrIte. Ammonia tests can't be measured while using PRIME, it won't work properly. Nitrite is the only indicator as to when the cycle is on its way down. All I can say is that it's working and that's good enough for me.
FWIW, and not to go too far OT, the trouble with hypo is that once you get the tank down to 1.09 SG, you REALLY need to monitor the pH, as it's very tuff to maintain in a hypo tank. I know this because we used to use hypo a lot. We're finding that quinine sulfate (Crypto Pro) does a much better job at killing ecto parasites and doesn't seem to trash the biofiltration system too badly.
Do they have a study to point to? I'd be interested in seeing it.
if Prime is the "magic bullet", then everyone would use it .