I am debating on a return pump for my 90gallon tank. The tank is drilled for .75" return and a 1" drain that is supposed to handle 600gph.

I figure I am between a mag7 and mag9.5. Here are the specs...
http://www.marinedepot.com/aquarium_powerheads_pumps_danner_mag_drive_supreme .asp?CartId=

The return will only be going from under the tank so that is about 5' maybe another foot or so under the tank to get to position. I plan to use flex tubing to minimize bending so there will be minimal pressure loss from that.

So really I am wondering if any has used or think a mag7 could be adequate? Even at 7' head it would still give me 4x turnover. I would really prefer to use the smallest adequate pump.

My other thought is that I may want to get my fuge flow from splitting some of the return off. I don't want to feed my fuge from the drain water because from reading I have done I think that is the dirtiest water and should go straight to the skimmer compartment. What kind of flow through the fuge would be good? (My fuge will serve purpose of growing macro and hopefully copepods.) The fuge will be 10-15 gallons depending on how much I cna reserve out of a 30g tank 36"x12"x16"

I have a 90gal with a mag 9.5. Even with the head height It is still too powerful. So with that being said, I would go with the mag7 or just dial down the mag9.5 with a ball valve. I am going to change mime over to a mag 7 and use my mag9.5 for a closed loop. You don't want alot of flow through your sump and fuge. Most skimmer work more effeciently with lower flow rates IME.

I have a mag7 on my 72 bow and it works great.
I would say go for the mag7

Great! Thanks for the input. I was thinking the mag7 from the numbers but not sure if those numbers really held up in a real world situation or what.

I am in the same boat as JR, I have a 90 with a 9.5, which I now think is a little too much. If I was to do it over, I'd probably go smaller. I'd probably look into having two Mag 5's, for a sort of redundant backup. I don't really plan to change it now, it seems to be working ok.

Not that it matters, you said your tank is drilled for a 3/4" and a 1". The Mag 7 is 1/2", and the Mag 9.5 is 3/4". If you choose the 7, you'll probably want to reduce the 3/4" to 1/2", and leave the drain 1". Another thing to consider is, for a 9.5, a single 1" drain is barely enough, or at least on my tank. I have an over-flow with a 1" drain, I am thinking about either adding a second over-flow, or drilling my existing over-flow to accept 1.25" instead. HTH

Yes I beleive a 1" drain is only good for about 600gph so the mag9.5 would be pushing more than that and overdoing it. I am definitely going with the 7 and shouldn't need to limit it at all.

Personally I would rather have double drains each of wich could handle the entire flow incase of issues with one. But I will only have the one.

If you can fork out the cash check on ebay. I use an eheim 1060 on my 90 rated at 600 gph.... couldn't ask for anything better.. you can look on ebay for an eheim 1260 (632 gph) and they last FOREVER.

Nick