How much flow would you like it to put out and also, do you need an internal or external pump or it doesn't matter? That will help us a bit more with some suggestions
Cool... I've always heard nothing, but great things about Sequence pumps. Here is a link where you can check out some prices and specs on them http://www.premiumaquatics.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=Sequence I've personally run (2) Quiet One pumps and they were relatively quiet I must say with the only exception of them adding a bit of heat to the tank. Not sure how much heat plays a factor for you, but the pump I used was 1506 gph, doesn't take up much space, can be used internally or externally and costs around $95 (it's the model 6000) http://www.premiumaquatics.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=quietone. Other than that, I guess the others will have to chime in, but one more pump I hear great things about as well which I want to try for my next pump will be an Eheim. The only problem is their biggest pump is only 898 gph so you'd have to run 2, but with the quality I hear you get as well as being quiet and not transfer much heat, it may be worth it if you have the space