Return pump ?

[bassist6108]

I'm about to buy a return pump for my tank/sump. I have read differing opinions on how much flow to have through the sump, but my drain is 1", and my head height will be about 3'. So, I was thinking a Mag5 would do the trick (and they are relatively inexpensive online), or a Mag 7, but with the 7 I would probably need to add a ballvalve to throttle it back a bit. Any suggestions on which way to go?

Thanks again,
Andrea

 

[auto_loader]

A standard 1" drain will handle about 600 GPH max. I think a mag 5 would be an OK choice with head pressure loss and all. With a Mag 7, like you said you would probably have to restrict the flow.

Its not a good idea to run your overflows at max capacity cause the 1st time a snail gets stuck in your overflow youve got yourself a nice mess to clean up.

 

[bassist6108]

Thanks much for the quick response!

 

[Vitaly]

<I>"I have read differing opinions on how much flow to have through the sump."</I>

I may be wrong, however, unless you are also planning to have a refugium within the sump you do not need to be overly concerned about flow through the sump. If you are planning to keep some type of macroalgae and grow pods, then you want to slow the velocity of flow. Velocity and volume of turnover through your display should certainly be focused on.


<I>"drain is 1"</I>

I second <B>auto_loader's</B> comment. Your drain will handle about 600 gph of water volume.


<I>"my head height will be about 3 [feet]"</I>.

I have not seen how you are planning to design your returns, but with that height you are looking at about:
* 353 gph with a Mag5
* 507 gph with a Mag7


<I>"probably need to add a ballvalve to throttle it back a bit."</I>

I have zero experience with this, but I would not think that the ball valve approach, though viable, is not a good long term strategy. I would imagine that the continuous, increased back pressure may be detrimental to the pump. But I do not know how durable these things really are.

I have seen designs where people who needed to reduce flow volume into their display, used a PVC "Tee" that will allowed them to divert a portion of water flow back into the sump. Sounds like this may be more ideal; though a bit more tricky.

Perhaps, someone else here may be able to comment/speak about this from experience.

 

[bassist6108]

Thank you for your response, Vitaly. Many people use the ball-valve approach to limiting the output on their return pump. I agree that it seems, logically, that it would put undue stress on the pump. At this time, I'm going to go with a Mag5, and if additional flow is needed, I may consider other closed loop options.

The option of t'ing off part of the return line seems a little extra messy (plumbing wise) for the relatively low maintenance design I'm trying to achieve. If you are looking for pictures of this kind of system, there are several if you do a search (when it is working). As for my system, Mag5 it is...

THanks for your reply.

 

[RobTop]

Mags are very durable pumps, easy to plum as they can be submerged(i've heard bad things about them external). I have 4 mag pumps in the fishroom. All are plumed with a union and ball vavle. this is for maintance purposes. If you ever need to get to the pump, you close off the vavles and open the unions as the pump is removable with out a mess.

As for flow through the pump I'm with Vitaly. Be more concerned with flow through the tank. Flow through the sump should be no more than what your filters can process in a given time. If your skimmer will process 300 gallons an hour, that's all you really need going through the sump. However to get the flow right through the tank a lot of ushave more flow through the sump. Take my 220, the skimmer has a mag 24 on it, but the returns move closer to 3600. That sole because the overflows can handle it, and the tank need the flow.

 

[bassist6108]

Thanks for the help, Rob. So, I guess I need to know how much my skimmer is rated for... any idea Vitaly?

 

[klasiksb]

I would go with a Mag 9.5 if your going to have some elbows and 45's. You may need to dial it down just a touch with a ballvalve, but it's better to have more pump than not enough. Mags don't handle pressure well and you'll loose more flow than you think you would.