As aquarium hobbyists, we all work with a wide variety of different challenges as we work with our aquariums and fish. On occasion when working with getting an issue like an ammonia spike under control in an emergency, water changes may not be fast enough or may make the situation somewhat worse by changing the water chemistry so rapidly. Products exist to help us with these situations, and they have names such as Amquel and Ammo Lock. The issue is after using one of these products to help get your ammonia situation under control while you prepare water changes and then get to the root of the cause, your water changes will give you false results.
Some ammonia test kits on the market today use what is called Nessler’s Reagent (Potassium tetraiodomercurate) as a part of the ammonia test. These reagent type test kits will not provide useful information when the ammonia neutralizing product is in the water. They may show a reading on a test kit which will indicate your efforts toward saving the aquarium residents are ineffective while what is really going on is the fish and/or inverts in the aquarium are starting to get some relief.
One example of a Salicylate based test kit, which is one which is not impacted by the use of ammonia locking liquids such as Amquel, is the API Ammonia Test Kit. This kit uses two reagents rather than the one that the Nessler based kits use. Seachem also has a test kit which will measure free ammonia, which is the ammonia that is dangerous to fish in the aquarium. Salicylate based test kits have become more common over the years, and while we are now likely to find kits which are not Nessler’s Reagent based, they do still exist. Keep this in mind the next time you are working to overcome an issue and have to employ some chemical help to reduce ammonia exposure for your fish.