Here is a fact given to me directly from SeaChem about using Prime to control ammonia.

It doesn't.


If you come home late or for whatever reason and your levels have gone wonky, you can add Prime (or Amquel or whatever) to the water to "lock" in ammonia. It won't change it, get rid of it, or change it into gold. It binds it into ammonium for about 30-48 hours, after that it changes right back into ammonia and is just as deadly as before. They did recommend in the event of an outbreak to add some Prime to the water and then begin doing frequent water changes to remove the ammonium before it can change back to the deadly ammonia.

I was reading some people debating bad test kits. I've never had an ammonia problem in a tank but I've heard that you can generally smell ammonia at the top of the tank at even the slightest levels. Maybe you could catch a whiff of of ammonia at your tank if the levels are as high as your kit says.