So I have a 20 gallon long with an AquaClear 50 and 40 gallon sponge filter filtering it. The inhabitants are: 5 cardinal tetras (I plan on adding one more) 2 Celebes rainbows (I might add one more, but not sure yet) 1 horseface loach (I was told one would do fine in my tank) 1 kribensis 3 lemon tetras (I plan on adding two more) 1 oto (I might add a few more, but not sure yet) In my AquaClear is the sponge, poly-fil, and half Matrix and half of my old biomax. I will be taking out the rest of the biomax and adding more biomax in 2 weeks. I do 40-50% weekly water changes and dose with Prime and Stability. My tank has been established for 2 years and I've had these fish for 4-5 months. Ph is 8.0, nitrites are 0, nitrates are consistent at 10-20, and ammonia is consistent at 0.25-0.50. I understand I'm overstocked, but my lfs won't take some of my fish and none of my friends or family have fish so at this point I either kill them just to get rid of them (which is inhumane and I'm not a killer of any kind) or I keep them (which is my only option at this point). So since I have to keep them is there anyway I can get ammonia to 0 and keep it at 0? I tested my tap water and ammonia is 0.