Tank flow rates

[uk-sub]

Hi Chaps
I was thinking about tank recirculation rates and pump sizes.
I'm in the process of setting up my 180g / 40g sump FOWLR system, it's reef ready with only one 1 1/4" return drain line, I have a mag 7 pump. My question is, is a mag 7 big enough for a 180 g tank. I've heard a mag 12 would be better. But I worry that if I spent the extra on the larger pump, it might pump too much water for the one 1 1/4" drain return I have...
Heeeeeelp!!
As always, thanks in advance

 

[wattsupdoc]

Is this a reef ready 180? And has a 1 1/4 return? What size drain and how many does it have? I would generally recommend a mag 24 for this. The 1 1/4 "RETURN" wont be a problem, but if your drain(s) cant keep up...that's the problem. An 1 1/4 drain I believe will handle 900 GPH. This is with a drain with air in it like most use. However with a pure water drain, like one that's throttled back and has the water level higher than the pipe, thus no air ion the line, you can get much greater(and quieter) flow. I'm not recommending doing this, as there are troubles involved with it, but just throwing that out there. A better method of this is Herbie's method which provides a backup drain. Google Herbie's standpipe for more info on that.
Generally speaking 10X through the sump is a good rate. So 1800 gph. What are you planning?Sump/fuge or something else?

 

[uk-sub]

Yep it's a reef ready with 1 11/4" return, and no other means of drain for the tank water. If a 11/4" drain will flow 900gph whats the biggest pump I can get up to 900 gph.....Or, as I suspect, is it not quite that simple?? Do I need a mag 24, 12 or will I be OK with a 7??

 

[wattsupdoc]

Do the mag 12, with a ball valve to control it.

 

[uk-sub]

Is a mag 12 what would give me the correct water circulation per hour? Or is it a case of get the most water circulation you can afford to pay for?
What pumps do most of you guys on here use for 180g set ups?

 

[small triggers]

I have a 150g w/ 2x odessey 1000's each 1340gph at base but i have about a 4 ft head so its down to like 920gph each. They are submersible.

 

[wattsupdoc]

I run 2 mag 7's (twins) on a 135 It just worked out that way for me. If all you have is one drain, and cant or don't want to do another, or some other method of draining, then you can only get so much through 1, 1 1/4 drain. So a mag 12 would get you there possibly a little throttled back.