whats the dif between total ammonia, free toxic ammonia?
 

total ammonia vs free toxic ammonia? please explain, the test kits don't tell you which one your measuring

Ammonia (NH₃) tends to convert to ammonium (NH₄⁺) in water. Ammonium is less dangerous to animals than ammonia because charged particles are more easily excluded by the cell membrane. The pH determines the ratio of those ions.

In addition, chemicals like Prime bind ammonia, but test kits often will undo the binding in the process of running the test, and detect ammonia that's actually bound and safe for the animals. Depending on how strictly the term is being used, some might count that as part of total ammonia. Which kit are you using, or is this more of learn-in-advance question?

When ammonia (NH3) is protonated it beccomes ammonium (NH4+) and is not or is much less toxic. The amount of ammonium ion formed is determined by pH. In the 7 to 8 range, a lot of the NH3 is in the protonated form.

Test kits measure total ammonia, that is NH3 and NH4+.