Sera NH4/NH3 Test Kit Ammonia – Monitoring Ammonia Levels in Water
Test for Ammonia NH3 / Ammonium NH4
High ammonium levels indicate a disturbed or not fully developed bacterial activity in the filter.
Ammonia (NH3) formed from ammonium (NH4) in case of pH values above 7 is especially dangerous.
Even ammonia values of 0.02 mg/l lead to gill damages in the long term.
Therefore you should always check the pH value in addition to the NH4 level.