Partial Closed Loop?

M

matt_longview

Quick question for plumbing guys.

I'm wanting to run a partial closed loop. Let me know if this will work.

I have a rack with three tanks, one on top of another and a sump below. Each tank has two bulkheads. I'm wanting one bulkhead to work an overflow and drain to the sump, and the other to tie into the external pumps (3600gph Dart) input to operate on a closed loop. I believe I would need to add a backflow valve on the bulkhead of each of the lower two tanks, and between the sump and the external pump. Then I can put a gate valve on the closed loop plumbing to choose my flow through the sump.

If anyone understands this well enough to give me some advise, please do! :)
 
So half of the bulkheads from the tank being plumbed straight into the input on the return pump and being kept out of the sump will work perfectly? Will it also reduce (I know not eliminate) head loss if those are kept underneath the water siphoning?
 
the bulk head for the close loop needs to be completely submersed, and not in an area air can be introduced. Not in a an overflow area. if it's coming from the overflow section you will have tons of micro bubbles. Pictures of the setup and hole placement would help.
 
It's not from an overflow section. It is a bulkhead approx half way up the side of the tank. I was thinking if needed I would put an elbow pointed down on it if it started to whirlpool.

I can try to get some pics up soon.
 
I spoke too soon earlier as I misread your post but even if it worked technically, a feed for a pump so large only 4 inches or so under water is likely to pull air even with a 90. Closed loops are really antiquated tho, your best bet is pumps in each tank. It will use less electricity and be less troublematic overall.
 
Just to clarify... I'm guessing each 1" bulkhead would pull between 700 and 800gph in that setup. 3600gph is without the head loss. With head loss I'm guessing it'll flow at 3000gph, I'll guess 800 to 1000gph through the sump so that'll leave 2000gph pulling through the bulkheads split across three bulkheads. So ~700gph will pull the air?

In that case I should be able to turn the gate valve a bit, reduce the flow through the siphoned returns and increase flow through the sump.

I'm not sure how trustworthy gate valves are in this setup either. I wouldn't want to plumb this and have gate valves in difficult to access places that could potentially (or rather will eventually) fail. So that's a roadblock as well.
 
Wait, so you want this pump to serve as your return and your 'closed loop' at the same time? As in a feed Line to the dart from each tank including the sump?
 
That's what I'm curious about. Is it possible?

Wait... more than possible. Is it a good idea?

I'm just looking for people to tell me this is a terrible idea. Or trustworthy people to tell me it's a good idea. From a "plumbing" perspective it should work perfectly. But while I know enough about plumbing I'm no expert.

I've got a 3600gph Dart, and a 1200gph Iwaki. I've got the Iwaki config figured out. That's no big deal if I choose to set it up. I'd use it as a simple return. The overflows would handle the flow just fine ect. The dart I think the overflows would be peaked (6, 1" bulkheads) but if three of them were siphoning it would seriously increase their ability to move water and I wouldn't be concerned at all. That's what started all of this mess in my head. The more I thought about it... the more it made "plumbing" sense. Thus I came to you guys to knock some sense into me. :)
 
Plus, if possible, using the dart gives me the no powerhead look, saving tank space and giving great flow through the tanks without too much sump flow. I tried talking to a reef buddy about the idea today. He seemed skeptical (as I am) but couldn't find the flaw (other than having to trust check valves).

Thanks for asking the questions, understanding what my idea here is and talking me out of it Wes. Just tell me why it's a bad idea. That's why I came! Haha.
 
not a good idea to use the return pump as a CL. Unless you have a very large sump and do not plan on having anything above the drain hole. When power goes out the water level will reduce to where the drain is. I wouldn't trust check valves to stop the water.

get 1 pump for the return and then get one pump for the CL system. however I would be concerned about feeding 3 tanks with 1 CL pump though concerned that the water is not put in each tank evenly. Causing one tank to overflow, you could try to regulate this with a gate valve(not ball valve). and you should not restrict water going to the dart only on the out put side.
 
I agree, not a good idea. I'm no plumbing expert but I will say this, you will at the very least have an incredibly hard juggling act with valves trying to get everything balanced. Even if you do get it working, you would be reliant on The check valves which aren't 100%, they will fail eventually, all it takes is a single snail wondering down to it. I plumbed my double stacked tanks with a single pump for returns and actually changed it to use two separate pumps because the balancing act was a pita, and I was only worrying about return flow. In hindsight I shouldn't have changed it because I broke the tank removing plumbing, but that's neither here nor there.

Let a return pump do it's job, return water, then grab a couple koralia 750's which only pull 5 watts each for flow. this will simplify everything, eliminate the chances for failure, and will be your best option. They're frag tanks right? Why do you care about the look, they should be functional and reliable, check valves aren't reliable and flow from returns is not functional for good flow.
 
Thanks for the push guys. I was on the edge... couldn't get past this idea on my own.

So I guess I need to buy a 300g so I can use this dart pump somewhere... ;-)
 
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