This should work...Right?

[mthornto]

I have posted a similar thread on the general discussion, but I started to think I might be better off posting here. Anyway, here's the situation. I have a 37 gallon cube (24x18x20) that I'm getting ready to drill for an overflow and closed loop. Initially I was thinking of a single drain and return for the overflow, and a single intake and two outlets for the closed loop. To make life easier, I thought that I would just drill all five for a 1" bulkhead.
I have a mag 7 that I can use as the return, which should end up giving about 500GPH. I don't have a pump picked out for the closed loop yet, but I'm shooting for about 600GPH. Most of the corals I'm looking at are listed as needing moderate or moderate to high flow on the Foster and Smith site, so that's what I'm looking for.
So what does everybody think; Does this seem reasonable? Would I be better off using 3/4" bulkheads for my returns? I swear, two days ago I was completely confident in this plan, but now I have my doubts. I really want to make sure I do this right, so any input is most welcome.

[Fish'InMN]

Go with the 1 inch bulkheads all around. No reason to complicate things and have to drill two different hole sizes for two different size bulkheads, especially when the larger pipe diameter will handle more flow, in case you decide to try SPS or something. ;)

Cheers,
Marty

[mthornto]

Great, that way I only have to buy one drill bit. What do you think about the closed loop outlets, I thought I might stagger them so that one is higher that the other and then putting them on a SCWD.

[Fish'InMN]

I've never liked SCWDs ("Squids"), as the current 3/4" model restricts flow too much (300gph max from each outlet) and are prone to failure after 6 months. Heck, I've read of more than one person that keeps extra Squids on hand so it is a quick change when they fail. Not "if" they fail, "when" they fail. I'm not 100% positive, but I don't believe it is a true on/off cycle either, but merely a reduction in flow from 100% to 50%.

Anyways! Position is a matter of personal preference, especially if you use the Squid, so I can't really say what is best. If your return is placed in the middle of the aquarium at the top, I would place a CL outlet as far apart on each side as possible, to distribute flow. Otherwise, you could have one arm of your CL go to a spray-bar behind your rock-work, to keep detritus from settling there. Lots of options, either way!

Cheers,
Marty

[mthornto]

I didn't know that about SCWDs. Maybe I'll scrap that idea, as I know all too well about things that are destined to fail. Do you know of another option that is more reliable?

[Fish'InMN]

The Oceans Motions products (Squirt, 4-Way, 8-Way) are the only others I can think of, but all of those are very pricey compared to the SCWD. Other than that, no options for a single-pump closed loop, unless you can DIY a sinusoidal valve.


Cheers,
Marty

[mthornto]

I'll look into those, thanks. Perhaps now I can spend spend a few minutes thinking about something other than this tank. Not likely, but perhaps.

[wooden_reefer]

I tend to think that you do not need 500 GPH for the open loop, but it doesn't hurt I suppose.

Why do you think you need 12X turnover for the open loop?

I am planning on 500 GPH for the open loop for my 150 gal, 2,500 GPH for the "closed loop".

[mthornto]

Well, there has been a new development. I want to use loc line for both the overflow and closed loop returns. Is there any reason not to go with 3/4" for the returns ( other than having to buy a second drill bit)?

[mthornto]

Wooden reefer,
It is not so much that I'm looking to get that much flow from the open loop, rather it is that I already have the mag. I will almost certainly have to throttle it back. In fact, one of my concerns is that once I do, I might not have the flow I'm looking for. I'm still trying to figure out what "moderate" flow is.

[Fish'InMN]

Yeah, those terms (High, Moderate, Low) are used very loosely and are dependent on your coral persona (SPS, LPS, softy).

As for the loc-line question, I again would say go with the 1 inch bulkhead and PVC. You can always reduce down to 3/4 threaded for the loc-line adapter, which is what we did on our setup. Send Danner (maker of the Mag series pumps) an email about pipe sizing if you have questions, they will undoubtedly tell you to increase the pipe size above the pump's output/input size. I guess the point I'm trying to get across is that there really isn't a reason to decrease pipe size, especially if you're already using the larger size for something else. But then again, I spend three hours a day doing pipe size/flow calculations, so I'm a little... :rollface: about it.

As for throttling back the pump, consider a T (with valve) directly above your return pump that dumps back into the sump, rather than just an inline valve. Also note that Mags have a tendency to draw more electricity than some pumps of similar capacity, which in turn heats the water more (especially when used internally/submerged).

Cheers,
Marty

[mthornto]

Yeah, thats sort of what I had in mind when I mentioned throttling back the pump; and I can certainly live with a PVC adapter. That is probably where I'll end up going, but I've had enough for now; it's time to call it a day. Thanks for the responses.