45 gallon. 50% once a week. fluval 306. stock- largely overstocked lol as I am moving half the fish into another 45 gallon, but I want to treat whatever this is first. To be exact I have 5 small id sharks, 4 small paroons, small black aro, baby tigrinus, 7 1-2" clown loaches, small flag tail, ghost knife, and 2 tiny peacock eels. The two 45 gallons are meant to be my growout tanks.