Experts - Question about setting up redundant return pumps

[dppitone]

To create redundancy for return pumping -

I'm planning on setting up a bank of four Mag 18s in my sump, all plumbed via 3/4" tube up and into a single 1 1/2" diameter manifold that will distribute the return water out to a series of tanks.

I'd put a check valve between each pump and the manifold, and install the manifold up at the highest elevation point needed for the returns. I'm hoping that with this setup, if one pump dies, the remaining pumps would maintain the proportional flow between the receiving tanks, albeit 75% of what it was when all four pumps were operating. Is this idea sound?

Also: for installing a return buypass to dial in the flow - can I install just one main buypass off the manifold. Or should I put a seperate buypass for each pump, between pump and respective check valve?

I get the feeling that if I use one main buypass, the loss of a pump would mess up the flow. But I'm not sure.

[dppitone]

I have the pumps and all other parts ready for assembly. I'm just not sure how to do the buypass.

[manderx]

just get 1 good external pump. it will be 1000x time more reliable than 4 mags. plus alot more efficient- less watts and alot less heat. 4 mag18s is 580 watts. probably around 40 bucks a month or more for you to run. the 3/4" plumbing and check valves will kill your flow. never seen a case where plumbing the outputs of multiple pumps was a good idea, since they end up fighting each other to some extent. for flow control, just put a valve on each tank. no need to do a bypass to relieve pressure. pumps just see the valve as more head pressure (and usually use less power at more head pressure).

if your worried about reliability, then get a second and keep it as a spare so you can swap it in without having to wait a day or two on shipping. you should have enough in-tank circulation anyway that having the return go down for the day shouldn't be much of an issue.

hammerhead is probably a good match, probably give a bunch more flow than 4 mag18s.
http://www.premiumaquatics.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=SQ-REEFLO13-SW&Category_Code=Sequence
you'll probably end up running 300-400 watts out of it, and a huge amount of heat will be kept out of the water. might even be able to sell the 4 mags to cover most of the cost of a hammerhead.

the next one down would probably work fine too.
http://www.premiumaquatics.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=SQ-REEFLO14-SW&Category_Code=Sequence

[dppitone]

Yes, I know it will cost a little more per month to run several pumps together. But I just prefer to have insurance against a situation where flow stops when I'm not around. It's happened to a lot of folks over the years. Between the redundant pumps and a UPS, I won't risk losing thousands of dollars of fish to suffocation.

[sjm817]

3/4" plumbing is an enormous flow restriction on a Mag18. You are supposed to use 1.5". If you are going to use 3/4" for a feed, you should consider pumps that will run well on small dia plumbing. Also, if you are that concerned about reliability, I would consider a different brand of pump. Not that Mags are unreliable, but there are better ones. JMO.

[dppitone]

Oh - I haven't received them yet, but thought from the specs that Mag 18s had 3/4 connections. I'll have to recheck.

[sjm817]

They do have 3/4" outputs. You have to double the output size.

[dppitone]

Yup. I see now. There are a lot of threads on that topic. So I'll run 1 1/2" tube up to a larger diameter manifold. Glad I asked. Thanks SJM.

[manderx]

But I just prefer to have insurance against a situation where flow stops when I'm not around. It's happened to a lot of folks over the years. Between the redundant pumps and a UPS

really? i can't think of many if any stories i've read about of tank deaths from a return pump that stopped pumping. are you frequently gone for days at a time? again, your fish won't suffocate because you should have plenty of in-tank flow provided by powerheads/closed loops. it just isn't practical to get all your flow from your return pump.

and you're going to put these pumps on a UPS? any idea how big it would have to be to run 4 mag18s for more than a few minutes?

i just don't see 4 mags as being anywhere close to being safer and more reliable than 1 good external pump. if anything, i see it as 4x the chance something will go wrong.

[dppitone]

manderx - Thanks for the help on the 3/4" tube size problem.

Yes, we go away for weekends. And no, the closed loops do not oxygenate the water. And third, the UPS is powered by natural gas and can run indefinitely.

I'd like to use external pumps, but the sump is sunk 2 feet into the basement floor. And there's no room to dig another hole to house external pumps next to the sump.