A few questions...
1. Are you sure that there are no dead or otherwise rotting ammonia sources in the tank?
2. Can you think of anything else you changed before you did this?
3. How long and in what state did you tank sit between batches of fish?
4. What kind of filtration are you using. Did you change the media between fish?
5. How many fish (what kind/size) do you have in the tank and how big is it?
I think okiemavis is getting you on the right track. Any product that says it lowers or some how keeps amonia in check is not a good solution. You are just adding to the "chemical soup" of the aquarium and not providing any real long-term solutions. Plus, its an expensive way to de-tox fish waste.
Often water changes are a MUST in this situation. You need to be treating the new water with a product like Stress Coat, Tap Water Conditioner, AquaSafe Water Conditioner, etc...