At family Thanksgiving dinner yesterday one of my nephews who had come in from Georgia asked about my fish tanks. So we started talking fish. He got started in the hobby about 20 yrs ago. He was telling me about his experiment with his 55 gal hex, he has a now 8 to 9 inch rotkiel, along with 6 lemon tetras, 5 cories, and 1 albino BN that's about 5 inch. He's had this set up with the severum over 3 yrs, he's had to replace a few lemons as they've died off. I asked about his maintenance routine, he said he does about 40% change every week to ten days without fail. He has an AC 110 running on it. I told him who am I to question what's working, but if I had tried this I would do my WC twice a week. He's more risk taking than me, he also has a 125 gal with an Oscar, a JD, a firemouth, a pink convict, 4 sun cats, 2 sailfin plecostomus, and something else I'm sure I'm forgetting. Maybe a terror, I forget. But he keeps up his WC schedule, whatever works I suppose.