What size pump do I need?

[Murminator]

Ok first some details I'm setting up a 90G perfecto reef ready with a 25G sump. The feed line looks to be a 1" 1/2 ID feed and a 1" ID return line to a split loc line nozzles all through 1 1/2 bulkheads. The tag on the tank says 700GPH. Now if I go higher GPH is it going to overflow the tank? It will probably be a little over a 4' head pressure. I want to go with a sumbersible pump I was thinking of a mag 9.5 but at 4' the head pressure is 800GPH will the overflow take it or will it cause a flood? or could I put in a ball valve to choke it down? dunno if this damages the pump or not or should I go with the Mag 7 that only has a 475 GPH head?
Please throw some idears my way I'm looking at getting a pump this week
Sorry for all the questions I new to all the overflows, sumps and pumps

[atcguy]

Perfect working order, I cleaned it well. Ready to sell 80 Bucks. Should be fine!!

[mr_alberta]

If your pump is too strong, you can always install a bypass and have it pump back into the sump.

[StirCrazy]

use the mag 9 and put a T on the outlet with a valve that you can put some water back to the sump then you can adjust the amount that goes back to the main tank.

Steve

[Montana]

you can always adjust the flow at the discharge, it is easier to do that then add more powerheads for the flow.

just my opinion

[Murminator]

Thanks for the idears I will probably go with the by pass option

[TheReefGeek]

I would go with a mag 7, especially with having just a 25g sump.

1. I don't like to max out the drains, asking for trouble
2. Too much flow through the sump can cause microbubble problems

If you haven't got the tank yet, I would get another 1.5" drain line installed for redundancy purposes, in case one drain line plugs. (even a partial blockage will cause trouble if you are pushing the drain close to its max.

Make sure your return section of the sump is small enough that your display tank can accomodate the extra water volume in case your overflows fail, then you wont flood at all. Installing a low-water shut off float switch for your return pump will keep it from burning out if this were to happen, but if you are using a cheap pump then no biggie.

Use durso's or similar to cut down on noise

Install egg-crate or similar over your overflow box to prevent unwanted visitors

[Richer]

Not sure what your plans for that 25g sump is... anyway you can build a fuge into it? You can use the bypass water to power the fuge.

-Rich