You said that the product that you bought from Petco was AMI. I was wondering if you meant API instead? If so that is a very good brand and as a Petco employee and Aquatic Expert there that is what I would recommend for the situation that you are having.
Personally, I don't use anything that removes ammonia for my water changes. Ammonia is the food for essential bacteria. I do have an ammonia remover on hand in case of emergency but have never used it.