how to select a return pump?

[mosesbrown]

I am looking for a return pump and Mag Drive is the pump that friends recommend. How do you know if you need a mag5, mag7, or mag9? I have a All Glass tank with a corner overflow and a 1" drain line. I am repacing the drain and return with a Mega Flow Kit. I know that is has to do with the height of the return and the flow thru rate but I do not see these stats for most pumps I see for sale online. Any help would be appreciated.

[bertoni]

I'd go for an Eheim over a Mag Drive, but you'll probably want to drive about 250-300 gph through the sump. MarineDepot.com shows graphs for at least some of their pumps.

[mosesbrown]

Is it better to have a higher gph. Like 500 to 700?

[mosesbrown]

Here are the ehiem pumps from marine depot. If I have a 3/4" return line should I be using the 1260 or is that too much pump?

1250 317 gph @ 6'7" 3/4" intake and 1/2" output
1260 635 gph @ 12'1" 1" intake and 3/4" output

This is where I get confused. If I buy a pump that has too much flow, will a ball valve cause back presure on the pump and overheating?

[bertoni]

This calculator will help with overflow and drain sizing:

http://reefcentral.com/calc/drain.php

For 250 gph, I get:

Drain and Overflow sizes are calculated as
Recommended minimum drain pipe diameter = 0.65 inches
Recommended minimum linear overflow size = 4 inches

So I think you'd be fine with the 1250.

Instead of a ball valve by itself, it's better to put a T in the return line and use a ball valve to direct part of the flow back into the sump.

[mosesbrown]

That a cool idea, never thought of the T and the ball valve. Thanks.

[bertoni]

You're welcome. Good luck!

[Tupps11]

How many timies per hour should the entire tanks water volume turn?

I have a 65 gallon, some pumps only turn that volume once per hour.

[sjm817]

Figure roughly 3 - 5x your display size after headloss.

[bertoni]

That's for the sump.

For the tank, I'd suggest 10x-30x the display size, or about 650 gph minimum.

[sjm817]

3 - 5x display size for the flow between the display and sump which is provided by the return pump. The majority of display turnover should be provided buy powerheads or a closed loop.

[mosesbrown]

I really appreciate all the input.
Unfortunatly, I think I am now more confused.
If my display tank is 75 Gallons plus the refusium is another 20 Gallons. How many times should the return pump turn over the tank volume. It looks like 10x for the tank and 5x for the sump. This seems to make no sense since the sump is smaller then the main tank. After reading everything I am between an Eheim 1260 and a Mag 7. I would welcome feedback on these pumps as well.

[sjm817]

75G x 3 - 5 = 225 - 375 GPH. Mag7s are really loud pumps. The Eheim 1260 is very quiet. It would put you over the 5x rate since it will have maybe 450 GPH or so after headloss. I'd say it was OK if you had a bigger sump, but since its only a 20G, I'd go with something smaller. A Mag5 would work, maybe an Ocean Runner 2500.

[AZDesertRat]

The Eheim or an OceanRunner 3500 should be about right. Both are better choices than the Mag since they are more efficient and create less heat. I know Drs Foster & Smith had OceanRunners on a great sale last week, about half the cost of Eheims and a little more efficient.

[zoomfish1]

I have a 75g w/20g sump and use a mag drive 9.5. I use the ball valve to turn it back about 25%. I run it in sump on a piece of styrofoam and it's quiet as a mouse.

[sjm817]

3500 would be kind of big wouldn't it?

[mosesbrown]

Sorry the sump is a 30 gallon tank that will hold no more than 20 gallons of water. I sounds like a Mag is a poor choice unless I want to buy a chiller at some point.

[AZDesertRat]

I use a 3500 with a 30G sump on a 100G main tank and its perfect as far as flow.

[sjm817]

My main beef with Mags especially the Mag7 is noise. The other thing is they lose so much flow one you connect the normal plumbing that is typically used. A "900 GPH" Mag9.5 flows just a tad more than a "635 GPH" Eheim 1260 once you connect 4' of plumbing to it.

With a 30G sump, the 1260 would be fine.