You can't tell the free ammonia from the taken-out ammonia unless you have the specific test kits. I'm pretty sure that the plant and the amquel are helping. Ammonia doesn't ness. make them gasp at the surface btw. Your ammonia will take a steep plunge at the time of the WC(aka you test then to see if you changed enough water, and if it works out you keep changing that much water) and then rise steadily throughout the rest of the time period.