Because I am partially disabled, and very short, I have my tank ( 55 gal) placed lower in height than is the norm, so that I don't have to stand on a stool to do any maintenance to the tank's interuor. I would really like to invest in a good canister filter, but the placement of a canister may prove problematic: I cannot bend down adequately in order to clean it. So far I have read that the canister must be positioned below the level of the tank. Is this true of all canisters? The table that supports my tank has room for the canister to sit right next to the tank. (I am not worried about esthetics) I could reach it easily at that height. Would using a canister rated for a lesser volume tank be enought to solve any flow pressure issues? I am assuming that a canister located below the tank would need more pressure in order to properly circulate the water. I am not sure if I am explaining my dilemma correctly. I really would prefer to use a canister.. (marineland).. But I cannot bend down or get on my knees to reach it for maintence, and raising the height of the tank is out of the questions. The difference in the height of the canister is only a matter of about a foot and a half.