i have a 20 gallon tank. i want to get a new filter because my current one is a bit out dated. my tank is a little crowded atm. 2 mollies, 2 platys, 1 skirt tetra, 2 redeye tetra, 1 dwarf gourami, 1 guppy, 1 small common pleco(will be upgrading) 1 angel(will be upgrading) 1 corycat and a yellow...