I was perusing the PetSmart site to see what they had for tanks and came across one I really liked. They had instructions listed with it and I was majorly confused as to why. The cleaning instructions are to "change only 25% of water once a month"? It was an aqueon product, 20 gallon hex. Any idea why would they have instructions to only clean the tank once a month? I contacted PetSmart and they couldn't answer why, said to contact aqueon. I did, they haven't responded yet. I've never seen a manufacturer give cleaning instructions so I honestly don't know if there is a reason for it or if they could just be discarded as "advice" if I were to purchase the tank.