RTR - Is that because with Nessler's reagent, it reads total ammonia (ammonia + ammonium) and Salicylate based tests only read ammonia? Also, how can I tell which type of kit I have? I don't have mine in front of me, but the last time I was trying to determine this, I couldn't find any indication in my kits (either on the boxes or in the enclosed literature). I've been using tetra test kits and Mardel test strips.