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Help with Closed Loop


steveoutlaw

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I'm getting ready to add a closed loop to my 135g and I need some help. The tank has 3 2" bulkheads across the back. I'm planning on using a 2800gph external pump through 2 SCWDs for a return. I was originally planning on using the center 2" bulkhead to feed the pump. Now I'm wondering if I should just use the center overflow to feed the sump/fuge and use the right and left bulkheads to feed the closed loop.

 

Thoughts?

 

I'd also like recommendations on an external pump to run 2 SCWDs. The pump can't be more than 2800gph at 0' head.

 

Thanks

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I would use all 3 holes to feed the pump. You would be surprised at the suction they can have. Just return all lines over the top. As far as pumps go, I like the Sequence pumps. Maybe the dart but I do think they could handle the pressure of the squids. It would be nice in the future to get a Oceans motion 4 way to run your closed loop. Can you tee off your return to feed your fuge?

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If the dart doesn't have the power, why not use a barracuda or a hammerhead. Why not just move up the scale to the right size?

 

fab

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The dart has the desired gph but I'm pretty sure its not rated for pressure. Scwds are only 3/4" and really knock down flow as they use the water pressure to divert the water from one side to another.

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My problem is that the SCWDs will only go up to 1400GPH.......times 2 that's 2800gph at 0' head (it's my understanding that closed loops have no head). The Sequence dart is 3200gph at 3' head. I wonder......if I were to use the dart to feed my skimmer as well........could I pull it off?

 

My other option is to just go with a MAG24 for the 2 SCWDs and have 2 SEIO M1500s running.

 

What do you think?

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Your closed loop will have head. Each 90 is said to add 1' of head pressure.

Friction alone will add to it. With 2 SCWDs, you will want a pressure pump.

I too would consider using all three holes as intake and run the returns up over the back.

You can make a slotted intake box(es) but the suction can be deadly with the

GPH you're listing.

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I agree, use those as overflows and plumb the SCWDs separately. I have only used one SCWD and have used it without a pressure pump. I think that it only needs current, not necessarily pressure, to switch. Also, like Chip said, each elbow and even any reduction in size of the pipe will result in head loss.

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Ok, I only have 3 2" bulkheads........I'm going to have to use something to feed the sump. What if I were to use 2 of them as intakes for the closed loop and 1 as an overflow?

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Two bulkheads for CL & one for return. How much through the sump? A single 2" can flow upwards of 2000 gph (according to RC's calc).

 

The CL bulkheads shouldn't be too much of an issue........unless you just use a flat bulkhead. Flat bulkhead & flat fish = issues (DAMHIKT).

 

I used these from Aquatic-Eco to disperse the flow. Depending on location (height) they can be hidden behind rocks........but......they are very large. Something similar but smaller?

 

Using a Dart on something with such a small opening will kill the flow (if not the pump), MDM recomends going no smaller than 1" on a Dart's output. One of the other models, 1" pressure rated or something like a GenX 55/100 would likely be better (though the GenX pumps are not silent).

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Erik - Nice to see you're still alive and kicking.......and hopefully playing a lot of golf.

 

I was planning on putting a bulkhead strainer on the 90 and turning the 90 so that it's facing the bottom of the tank. I think that the SCWDs are going to kill the flow enough that it won't pose too much of a problem.

 

My other option is to just use a Mag24 as a return pump and use all 3 bulkheads as overflows.

 

Decisions, decisions.......

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and hopefully playing a lot of golf

Not enough........at least thats what the scorecard says.

 

I was planning on putting a bulkhead strainer on the 90 and turning the 90 so that it's facing the bottom of the tank

Might have an issue, might not - one of those never know till you try deals.

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Erik - Nice to see you're still alive and kicking.......and hopefully playing a lot of golf.

 

I was planning on putting a bulkhead strainer on the 90 and turning the 90 so that it's facing the bottom of the tank. I think that the SCWDs are going to kill the flow enough that it won't pose too much of a problem.

 

My other option is to just use a Mag24 as a return pump and use all 3 bulkheads as overflows.

 

Decisions, decisions.......

 

IMHO, you will burn up a Mag24 in no time. These pumps are not meant to be used 'dry'...

 

-- Rob

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1) depends on how low on back of your tank your 3 holes are drilled as to whether you can use for closed loop.

 

If they are only a few inches from the top, you will be sucking air if you use a big pump - at least that is my opinion. Sounds as if they are near top of tank with your original intent to use as drains to feed sump.

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1) depends on how low on back of your tank your 3 holes are drilled as to whether you can use for closed loop.

 

If they are only a few inches from the top, you will be sucking air if you use a big pump - at least that is my opinion. Sounds as if they are near top of tank with your original intent to use as drains to feed sump.

 

I was planning on using a 90 facing downward and can even add 2 or 3 inches of 2" pipe. I'm thinking that maybe I just need to use all 3 as overflows and get a big burly return pump to run through 2 or 3 SCWDs.

 

Rob - I was talking about using the mag 24 submersed as a return pump.

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Hey Steve, post a picture of the back of the tank (if you can get it) so we know what is going on back there. I don't recall seeing bulkheads in the pictures you had before but could easily have missed them.

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I'm not going to answer, I just don't like the way that tank is giving me the finger :lol:

 

Seriously - 2" 90* with a section of drilled pipe = disperse the flow??????

 

Something like this

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2 thoughts from my limited experience.

 

The Mag24 will be way LOUD if you run it external. It works, and mine didn't leak, but even in the basement on a piece of closed cell foam with flexible connections it seemed like the whole house was vibrating. At least that's what my wife thought. Putting it under water made it at least bearable, but it is still a loud pump (have since switched to Iwaki 70 for a return).

 

As for reduced flow through a scwd, have you considered this mod: http://www.nano-reef.com/forums/index.php?showtopic=76847? I did something similar, but simpler. I just cut off the bottom (input) to make a hole big enough for a 1 1/4 " female adaptor. I cut off the slip part of the adaptor and then glued the threaded part to the scwd using Weld-On #16. I now have 1 1/4 inch plumbing all the way from my sump right up until it enters the scwd. I haven't done any flow measurements yet, but I had the same pump going through 1 inch tubing to an unmodified scwd before, and I now get much, much more flow even with the pump's output throttled way back. Another benefit is that when the scwd stops working, it is relatively easy to unscrew and gain access to the gears to clean them out. The negatives are that it doesn't seem to switch sides as quickly (less concentrated flow over the internal propeller, I believe) and I tried to replicate this with a different scwd and a 1 inch adaptor and ended up ruining the scwd. Probably more due to my lack of real skills than any fault in the design. I suspect that it could probably handle much more than 1400 gph with this mod, and I am certain it doesn't cause as much head loss.

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