# Overflow plumbing WTF?



## Thalas_shaya (Mar 10, 2014)

Hey folks, so I have a big tank that I bought a zillion years ago. Because...life has been happening, I'm only now getting around to setting it up. And I'm not totally clear on what I have here. The tank was a custom build, used as a frag tank in a fish store. The thing is like a 110 tall, but rotated 90 degrees so that it's deep front-to-back instead of top-to-bottom. As a result, the footprint is 48 x 30 (in) and the back overflow is where I'm stuck. 
It's pretty big, and has weir notches in it, but also a bigger notch that I suspect is for the return. 
Here's a link to a pic:









The notch in question is circled in red.

So Here are all the parts I've got. 








The one highlighted yellow is the return, I think. It is the right height and diameter to fit into the notch, and it connects to the longer clear hose marked in green.

The red circle indicates the trash can and fireplace tools that are in the tank to keep my toddler from throwing them down on my tile floor to hear the lovely crashing sounds they make and see the funny colors mom's face can turn. 
I think the piece marked in red might be for a protein skimmer (not shown) but it has an intriguing valve on it. 
The blue piece looks like a plug that just stops flow at a bulkhead. 
The ones with question marks are a straight length of pipe and maybe a reducer with a female threaded connection? I don't know what they're for.

Here is a pic of the inside of the overflow box:









The pipe looks like a Durso overflow with a downturned intake and the blue circle highlighting an air hole drilled in the cap. 
The red circles show the three holes drilled through the tank. The outer two are larger, maybe 1.5"? The inner one is smaller, maybe 1.25"? I can't get the standpipe out because of the fittings (not shown) between tank and sump, but there's no valve like you'd expect from a Herbie overflow. Also, I know that the standpipe connects to the shorter clear tubing (highlighted green in shot of misc. pipes) and that it runs into a filter sock in a lidded chamber of the sump. So that seems pretty straightforward.

My best guess is that maybe they intended to do a Beananimal or a Herbie with a return, or maybe wanted a second drain next to a Herbie for a refugium or something, but instead (I'm sure there were reasons) they did a Durso with a return and used the short capped pipe to plug that third hole. Then the long clear tube went from the return pump through the smaller central hole and through the return pipe routed through the notch in the weir. 
Anybody got any better theories? Does this look like something else that I'm not familiar with?

Here's an article with a brief explanation of Herbie, Durso, and Beananimal overflow arrangements


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## Thalas_shaya (Mar 10, 2014)

Images are broken. *sigh*
If I can figure out how to edit the original, I will. If not, I'll try to troubleshoot the images and repost.


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## Thalas_shaya (Mar 10, 2014)




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## Thalas_shaya (Mar 10, 2014)

Link to Parts Pic:

Red circle = Ignore. Toddler-proofing.
Green highlight = Known connection from plumbing to sump, long return and shorter drain
Yellow highlight = Suspected return pipe
Blue highlight = Suspected cap
Red highlight = Suspected part of protein skimmer. Has a neat-looking valve at the end, might be useful?
Black question marks = ?????


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## Thalas_shaya (Mar 10, 2014)

Overflow Interior shot. Two outer holes are same size, about 1.5", central hole is smaller about 1.25"
Red circles = drilled holes
Blue circle = hole in cap for Durso (?) standpipe


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## nodima (Oct 3, 2002)

The extra wide "tooth" in the wier is most likely for a return tube/pipe, based on it's shape.

The three drilled holes are for the main overflow, the extra "Just in case" overflow, and the smaller hole is the return.

The hole in the top of the pvc overflow tubing allows air in to reduce noise and the flushing sounds that can happen without it.

I don't see a third picture with all the parts, however.

The picture with the three holes looks like a pretty normal overflow piping set up for the main drain. There is a lot of flexibility in how one sets up an overflow as you've seen from your research. FWIW- the overflows that come with Marineland tanks look very similar to the pvc in your picture, except they don't add the short vertical piece above the elbow, and just drill the elbow itself.


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## Thalas_shaya (Mar 10, 2014)

Hrmmm. Not sure why the pipes pic isn't showing for you. I'll poke at it and see if I can suss it out. Thanks for the response! I'm thinking that since I have the two drain holes I'll do a Herbie with it and discard the existing Durso.


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## fmueller (Jan 11, 2004)

I think between you and nodima you have pretty well figured out what is what.

Personally, I have always been a huge fan of Durso overflows - simple and effective. But then I had my tank custom made, and put a bulkhead for a 2" pipe in each of my two overflow boxes. Restricted flow was not exactly an issue. ;-)

With a Herbie you should be able to get more flow, but the concept has always creeped me out a bit. If you loose that suction effect, it's not funny. That's why you need an emergency overflow. But then, why not use two Dursos and be done with it? If you are worried about the Durso clogging up, you can use a strainer just like on the Herbie.

Also, why anybody would want to bring a return pipe back through the bottom of the tank and through the overflow box eludes me. It just seems unnecessarily complicated, and you have an extra bulkhead. If a system leaks, it is *always* at a bulkhead, so the fewer of them you have, the better.

If you want to maximize flow, and since you have three bulkheads to deal with anyhow, why not put three Dursos and bring the return over the rear wall of the tank? That's what I would do, but that's just me.

If you don't have space for three Dursos in the box, because of the bit that sticks out at the side, I made mine to look like this. That design also prevents clogging very effectively. You don't need a strainer.


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## GulfCoastGuy (Aug 5, 2018)

Fmueller's observations about the potential of leaks at bulkheads is spot on but the holes in the tank are already there. Whether the hole is used to pass water to or from the sump or it is plugged, at this point to me, seems academic. The potential for a leak remains the same. That said ...

I am an unapologetic advocate of valved multi-drain overflow designs so I'll offer a counterpoint to fmueller's points in favor of the Durso free-running single drain.

The most important positive for the former is reserve redundancy. In both the Herbie and the Beananimal one of the drains is held in reserve as an emergency backup in the event the main drain is somehow compromised. To me it just makes sense to design in a backup with the design criteria being the backup drain must have the capacity to flow the entire load of the original drain, at the return pump's full delivery capacity.

Valved drains running at full siphon when properly tuned are, themselves, silent. I run a Herbie on mine. It's a Waterbox 60" x 26" footprint. It is marketed that way as are all the tanks in the Reefer series from Red Sea. At night, when I shut down everything to go to bed and the house is quietest the only thing I hear is the waterfall like sound from the overflow and occasionally a bump like sound as the ATO pump comes on.

Full siphon drains flow an incredible amount of water. Far more than that of a vented drain.

Down side. This is not a 'set and forget' system. It must be tuned and on occasion adjusted to compensate for tank dynamics;buildup in pipes, pump aging, even in rare cases simple work in the tank can cause disruptions that will either require time for the system to resettle or a readjustment of the main drain flow. Part of the beauty of the design is that the system inherently alarms you of the need. As water level in the OF box creeps lower the main drain will form a vortex and draw air, making noise to draw your attention. Likewise if the water level creeps up the emergency drain will get noisy. Usually a very small adjustment is all that is required to bring the system back to balance and silence.

You already have the holes in the tank. Plug 'em or use 'em, they're there, under the same hydraulic pressure and pose the same leak threat.

Here's a link to a good write-up on the three designs and an exhaustive one on the Herbie. Keep in mind they are written by a valved-drain advocate.

http://gmacreef.com/aquarium-overflows-durso-herbie-and-bean-setups/
http://gmacreef.com/herbie-overflow-reef-tank-plumbing-method-basics/


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## Thalas_shaya (Mar 10, 2014)

Thanks for all the replies, y'all. GCG, I love the GMACReef articles.  I'm personally a Herbie fan myself, because a silent siphon and its increased flow capacity appeal, as does the emergency overflow drain. I used to do fluid dynamics modeling in a previous incarnation of my career, so I like the elegance of the system and how it solves the noise and capacity problems. Plus, I think it's doofy to have a hole drilled and then stick a cap on it. 
I hadn't considered multiple Dursos, and I have great love for the space-saving Durso design you shared, fmueller. I'm going to sleep on that, as I also have a great love for low-maintenance!


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