i have a 100 gallon tank with a fluval 404 canister filter, a surface skimmer powered by an aquaclear mini power filter with the sponge and carbon package, an AC802 powerhead with the filtration attatchment filled with those ammonia killing rocks, 5 piranha's, 1 sailfin pleco, 2 fake plants and a few live plants, water parameters are all normal nitrite-0ppm, ammonia-0ppm, Ph-7.2, and nitrate os about 20 ppm. i dont know hardness, im gettin a hardness tester tomorrow.