If I recall correctly, prime doesn't do anything to help the "protective slime coat" of the fish. Aquasafe does. These stress coat aids work in one of two ways: they irritate the fish causing it to create a thicker slimecoat, or they contained a compound to my best understanding binds organic material (like slime on the fish).
If all the stuff does is get rid of chlorine/chloramine/heavy metals, you should be good. If it has anything that is suposed to help the slime coat or stress coat of the fish, too much could be a problem.
I was using something that has these organic compounds, and I don't know if it was the poor cycle, or the compounds, but I had tons of microbubbles in my freshwater tank. I only had a 2.5ish gallon bucket at the time to change water, and gave it a generous squirt every time...probably enough to treat 15-20 gallons.
This could be just coincidental, or it could be cause and effect. I don't know, and haven't tested enough to try.