im using a hang on tank magnum canister filter for a filter on my 50 gallon tank. it is rated for aquariums up to 55 gallons and it pumps 250 gallons per hour. im trying to get a single tiger oscar in it and i heard they are very messy fish. is there any way to improve on the filtration without buying another filter? i would probably do 25 percent water changes every week, and btw how do u guys clean ur gravel without picking up gravel too? thanks in advance 
