So I have a 20 gallon quarantine tank that I set up a couple of months ago, store water from my partial water changes and some rock from the tank for several weeks before putting them in the QT tank. When I install it, just put in 50% water and 50% new water to start, put in a small wave generator and HOB filter, put in sponge to store bacteria and some ceramic rings from my main tank, that was in June , I have a couple of fish since last August 4th (Coral beauty angelfish % damselfish) and since always my ammonia test has read 0.25 ppm, I use API test and I have read about the false readings, but doing the ammonia test in my main tank has always shown 0 . Since I have fish the test has marked 0.50 on occasions, I have made water changes every 72 hours since I have them, fortunately they have never stopped eating and they are not sick either, I bought AmGuard from Seachem to help me a little, for several days I have I'm using after each water change, but I see that the ammonia readings still do not drop below 0.25, so does AmGuard alter the test result? Should I add more biological elements to my main tank? I have read that in 10 and 20 gallon tanks the biological filtration is poor, I think I realize that, by the way, every night I remove my fish waste and unused food, my tank has bare glass, PVC and rock , and if the fish show any signs of disease then they will be removed and treated in a hospital tank. I also change the mechanical filtration material daily since using AmGuard, so what am I doing wrong? I have thought about cleaning the HOB filter thoroughly, without touching the sponge or my ceramic rings, let me know your opinions.