magnum 350s to move water both ways

almo75

almo75

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Feb 6, 2008
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Corn fields south of Chicago
Real Name
Al
Hello everyone,
I had an idea last night and checked posts this morning for conflicting info, that I may have found. Someone asked about using a canister filter as a return pump and was advised against it. Here is what I was thinking...Can I use 2 magnum 350s to deliver and return water from a 10 gallon tank under my stand? The goal is just to get the heater and skimmer out of the tank for a cleaner look. Just like you would think...one pulls from the Display and dumps into the 10 and the other brings it back. I ask because I have a 350 and a buddy has another I can get for next to nothing, perhaps even nothing. I figured slight differences in flow due to age could be compensated for via the quick disconnects valves. They should be close as is. I realize there will be a difference due to gravity helping on one side and hurting on the other. Does anyone see this as an insurmountable difference? Also, how do you guys regulate return flow when you use an overflow box to go to the sump? Just a simple valve or something?
I appreciate any advise offered!
Al
 
I don't think I would do it myself. I see what your trying to do and why you think it may work.. but here is the problem. Your return pump has to be closely matched to the pump pulling or else your pump pulling water down to your sump will go faster than the pump pushing water back up (due to gravity) and your sump will overflow.

On an overflow box, you just get one that is rated for the correct GPH to match the return pump. For me, I have a 600GPH overflow box, and a 700GPH return pump that puts out around 575GPH once you take in account the vertical lift from the sump. So my overflow and return pump are just about matched evenly. If you have a bigger return pump than your overflow can handle, you can T off the return back into your sump to reduce the flow. Some people put a valve but that is not recommended as pumps don't like to be restricted in that manner.

If your canister filters can be adjusted for flow, then it may work, otherwise your going to have to somehow reduce the flow from your canister pulling water out of the tank, but again, most pumps don't like that being done to them and it reduces their lifespan.
 
Eh I wouldn't do it for the reasons Ace mentioned above. You'll never get the pumps going exactly right, and if a snail or small piece of macro gets stuck to one while you're out, you could end up with a flood situation very fast. Can it be done? Sure. Should it? Well, it would be a tenuous balance at best, and I have dumped enough water on my floor to steer away from solutions that are not very robust. Besides, I don't know what you're paying for Mag 350s, but for the same price you can probably get a HOB overflow box and a return pump and do it right.
 
What about this...
Place the inlet for the 350 close to the top of the display tank, so if something happens, it won't be drained too much. Run that line into the 10 below ( put a ball valve inline to restrict flow, or stop it all together) ... let it siphon into the 10. You'll have to calculate the level of the intake in the display tank so the system wont siphon more water into the 10 than it can hold. then use the 350 to pump the water from the 10, back into the display tank. restrict the flow of the 350 to a little more than the siphon. this way the pump will draw the water through the 10 gal tank, if the power goes out, or the pump dies, then the display tank will only drain to the level of the input to the 10 gal tank. I have thought about this as well, to eliminate the 3 stealths in my 125, but have not tried it yet... might have to now... I was going to use my existing FX5 for the pump.. My inlet would hae to be about 1 1/2 inches from the surface..

And, you could put a solenoid valve, for a sprinkler system, in the siphon line, so if power to the pump fails, the valve will close, and stop the siphon..

Hummmm.. Maybe I should try this now...
 
Appreciate the guidance guys! Ace, what do you do to compensate for the difference you spoke of? 600gph coming out and 575 going back. Seems a 25 gallon mess an hour. A valve on the bleed off back to the sump since it does have one free flowing outlet? Is valving that OK?
I was actually looking to use this idea as a cheat, having my mechanical and chemical filtration done through the canisters, that way all I need in the makeshift sump is added Biological filtering which in my mind would not require the addition of any baffles. Any problem with using the 350 as the overflow and a T'd return pump for return? Return pump being rated higher. Sploke, you bring a legit point about possible blockage. I'll give that more thought. I just hate to see my pile of unused equipment grow as I spend $$ on new stuff. I am sure you guys have your own stock piles too!
 
Well, if the pump is pushing 575 at the tank, and the overflow is rated UP TO 600GPH, then it will handle it.. the overflow will only take out as much water as the pump puts in the tank. I can put a 50GPH pump and the overflow will work fine. It is only when you start pushing more water into the tank than your overflow can handle that becomes a problem. With your situation, your talking about using a pump to actually suck/pull the water from the tank. The overflow doesn't actually pull the water per se, it just drains it like a sink drains water.

Say your drain in your sink is 1".. but you put a firehose to your sink.. your sink won't be able to drain that much water volume and will fill up and overflow. Where as, if you put a garden hose to your sink, the drain is big enough to handle that much water and you never have a problem.
 
Ace, I believe you pointed out what I was missing. I was under the impression that gravity would pull the full flow rate regardless of what was being pumped back into the tank. That is why I assumed the 25gph on the floor. Did you see a problem with the 350 as the intake with a regular return pump going back? It is the mechanical filtration aspect that has my mind stuck on this. I always enjoy building something more than buying. I'd build everything myself if I could!
 
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