Mag 5 return pump good for 40 gallon display?

Just as the title says, is a mag 5 return pump good for a 40 gallon display. 20 High sump, no more than 4-5 ft of head.

 

If you mean a Danner Mag-drive 5 (500gph), then yeah.... I would say that's possibly even a bit overkill for a 60gal total volume system. not much, but you may consider using a valve or bypass back to the sump to control flow.

Of course, always to go a bit overkill and find a way to restrict flow than to not have enough flow to start with.

I would also say that that pump alone may not give you adequate flow in the tank, so you'll still probably want some powerheads of some fashion. But as your question is posed, then I would say the answer is yes.

 

I have a MAG 3 running my 50 gallon. You have more than enough with a MAG 5

 

I would add that the issue of flow for the sump's filtration functions is secondary to the use of a larger-than-necessary return pump for added flow/agitation of the display tanks water. Asking if a certain GPH is "enough" for proper flow or current production via a single or even split return nozzle, the answer is almost always "no". For optimal flow in the DT you will want dedicated power heads and/or a closed loop circulation system. Unless you're running a bare bottom fish only tank, then you're probably ok.

At the strictly utilitarian level, a sump shouldn't need more than say 2x the tank volume per hour flow, if that.... Refugiums thrive with even less flow. A skimmer can only process the water its own pump is capable of moving, gas exchange is almost instant when the water is agitated, the various probes and meters don't care, and any additional filtration via live rock in a sump is a process that takes days or weeks to complete the journey of the water through the pores of the rock to get to the deeper anaerobic bacteria.

Surface skimming and removal of suspended particulates would be the only practical reasons for higher flowrates to a sump I can think of, and I would have to say 500gph will be more than enough for that.

 

Sounds great. I am currently using two Koralia 750gph as wavemakers alternating on and off every 10 seconds, programmed through my Reefkeeper Lite Controller. Would these and the return coming from the pump be too much flow? I could split the pvc return so that it returns water at each end of the tank right?