Your pretty well stuck with whatever pump Coralife offers as a replacment. Just call ESU on the toll free number and they will have you one on the way in short order. Its a RIO, and IIRC its a 360 or 380 gph in size......but the gotcha is the front cover piece and pumps plastic housing needs to be able to accomodate that mneedle wheel of theirs unless your into a lot of modding and experimenting. Best bet on the CSS line is OEM pumps.