To add onto small pumps, I upgraded my pump in the Fluval Sea Evo XII. If anyone else has the same tank they know that the pump will do the job but doesn't have the best flow rate and fits very snug into the back chamber. The "factory pump" is rated at 134 gph I believe, or something around that. I upgraded to a Hydor Centrifugal pump. It is about half the size, quiet, and pushes 300gph. I am able to control the flow rate as well. The pump paired with a hydor nano powerhead pushing 240gph allows me to turn over the tank at most 40 times an hour. If anyone has a tank around the same size, and is looking to save a considerable amount of space, I highly recommend this pump. The dimensions are 2 3/4"L x 1 1/2"W x 3 1/4"H