DIY overflow box

DIY overflow box

I am in the process of trying the same thing for my 180g. The person I bought the tank from give me a HOB OF he used for the tank. I had a HOB when I first got in the hobby and flooded once when the siphon broke because of a snail. I will never do that again LOL.

So far I have cut the tops off and added a third 1" drain hole in the outside box. Waiting on the 1.5" bulkheads, gaskets and glass hole saw to get in before I cut the holes in the boxes.
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Also nice job on the foam wall. It will be covered with Coraline algae after 6 months or so. I did the same thing for my current 180g tank to cove the huge OF.
8c841155c341bd69ef7caeafa1bf9639.jpg
 
The ghost OF I am working on is for my new 180. I will drill the holes about a inch or so below the plastic trim. Just where ever works for the two boxes and tank. My bulkheads will be here this week so I will be able to really plan further once I have them in hand. I want both boxes to be snug against the rim and the holes close to center on the inside OF box.
 
My only concern is the amount of space between the emergency drain and the top of the external box. You want the hole to be just below the teeth on the internal box right?
 
I am designing mine kind of like the large eshopps eclipse. The internal box has the bulkhead holes toward the middle of the box and a little higher than mid way for the external box. The emergency drain should be around the top of the bulkhead in the back box from what I've seen which should be a few inches from the top.
 
SFish said:
Ok so questions

1) what size bulkhead should I use to connect the internal and external box together? I would use 1.5 inch bulk heads so that you know there will be enough to handle any amount of flow you are going to use

2) would I have to use 1 1/2" PVC to go from the external box to the sump then?
You can use 1 inch for this. Unless you plan on doing over 2000gph
3) would I need to use two 90's to make one of these or do I not need that U shaped pipe?you can use either or on this one



4) will a bulkhead be ok supporting the weight of the boxes?from what I can tell with all the pre manufactured ones the bulkheads shouldn't have any issue holding them up but if it seems iffy I am considering adding a glass edge I might silicone under the outside box

5) about how big do you think I would have to make the external box? I would make it similar to what other manufactures are using in compare to the size of your internal box but usually the outside box is a little larger than the inside box

6) how far from the top of the trim should the internal box be? it looks like most people install the boxes just about all the way against the rim. I plan on having mine barely touching the outside rim. It all depends on where you want your water level.

7) about where should the hole be that connects the two boxes in relation to the internal box? Do I want the top of the hole just below the teeth of the overflow? I would have the holes in the middle of the internal box so that there is more between the edge of the box and the edge of the hole. I plan on making the holes in my internal box in the dead center of the box. Then I will place the internal box against the rim so I can mark where I need to drill the glass. After I drill the glass I will place the extranal box against the rim and then mark and cut hole accordingly
Click to expand...
 
That won't make noise if the hole is in the middle of the internal box? My return line is 1" so I would be ok with 1" PVC on the overflow i'll only be pushing 500gph?

By the way thanks a ton for your help.
 
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If you want the water level in the internal box higher for less noise then you might want to have the bulkheads located a little higher up than the middle. I didn't think about that part since noise isn't a issue since my tank will be in wall
 
One because of the amount of space. Two would not fit. Because of space is also why I'm using a Herbie overflow.

So if I use a 1 1/2 bulkhead I have to be 1 1/2 inches from the top and the side right?
 
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What size boxes are you planning on using? I think if you have a 1.5" bulkhead going through the boxes and tank with two 1" drains you will be fine. If you can make one of the 1" drains a full syphon with 2 elbows or the U fitting and a valve to get the syphon right. The second drain I would just leave a standing pipe and would have it go to almost the top of the bulkhead that runs through the tank.
You could look at this as a size reference. https://www.saltwateraquarium.com/eclipse-s-overflow-box-eshopps/
As long as the boxes are the same size or bigger you should be good. Also look into getting extra gaskets for the bulkhead that runs through the tank and boxes
 
The inside box would be 7 1/4 L x 3 W x 8 1/2 H inches

The outside 10 L x 4 1/2 W x ?

I haven't decided on the height to go yet. I know that the emergency drain is supposed to be 6" above the regular drain. The outside trim is about 1" I think. I was planning on putting the outside box right under it. I would like to go with 2 or 3 inches of space above the emergency drain is a fail safe. My dilemma is if I put the bulkhead head in the middle of the box is that going to create a waterfall effect in the internal box which would make noise? I could possibly lower the internal overflow some but not sure by how much as my rock wall will limit that. I may have to make the internal box shorter. I have looked at that picture before I posted. I was thinking to go with 1 1/4" bulkheads but at the same time all the premade boxes have 1". I did read that for the emergency drain a 1" pipe could only handle 330gph so at the very least I want that pipe 1 1/4". My guess on the height would be 10".

6 for the gap
2 of dead space above the drain
1 for the normal drain

I don't really want to put that U pipe in unless I have to because of space. What is it supposed to do? This is what I've been using as a guide

http://gmacreef.com/herbie-overflow-reef-tank-plumbing-method-basics/
 
That was an interesting read. Honestly I had never really seen a set number on the height of the emergency drain. Not saying I disagree with anything. I've always run the emergency drain 2" or so above the syphon. But I am also not an expert by any means but I can tell you a thousand ways not to do something.
As far as the bulkhead height I would put it further up on the internal box to help keep noise down. I might actually do the same with mine now that you mention it. That's one of the nice things about DIY is if you mess up you can try again. May cost an arm and a leg in the end depending on the project but atleast in this case it would just mean making a new box. Another thing too is a 1" drain at full syphon that drops atleast 2 feet can handle 1700gph according to beans website.
http://www.beananimal.com/articles/hydraulics-for-the-aquarist.aspx
The HOB boxes I'm using measure (all OD)
Internal: 10.5"L x 6" T x 2.5"W
External: 10.5"L x 8.25"T x 4.5"W with (3) 1" drains
I plan on running atleast 1200gph. If the boxes can't handle it then I can just make bigger ones if need be with larger diameter drains.
 
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