# Overflow construction! please some help!



## anonimus (Nov 9, 2012)

In Mexico is too hard to get an overflow like this one:










So, I decided to do my own... But I have some questions about it...

My tank is of 240 liters, and my sump, is of 40 liters, for now I have this controled with two bombs (one from tank to sump and one from sump to tank...










My problem are the measures of my overflow. I dont know if im in the right way on construction, Im worried about a power outage and the water downing from the overflow to my tank, how can I control this?

this is a simple diagram I made to building my overflow. Can we take a look to help me on the wrong measures?










Also I dont know wich size should be in the holes! :-? :-? :-? :-? :-? :-? :-?


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## cantrell00 (Oct 30, 2010)

glass-holes.com


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## b3w4r3 (Dec 14, 2012)

Do you have access to PVC pipe? There are many DIY articles around for constructing an overflow out of PVC pipe only. They are kind of unsightly, and I don't like that you can't see the water in them, but a lot of people have been using them.

One potential problem I see with your diagram is there isn't a way to change the height of the skimmer box (the retail unit looks like it has a couple set screws to raise or lower the whole thing). The position of it will determine the water line in the tank, and it's nice to be able to adjust it if needed. As far as the holes are concerned, they will be determined by the bulkhead size you use. Make sure you select a large enough bulkhead that is rated higher than your return pump at the current head pressure. The hole in the top is for starting the siphon so whichever fitting you use, it will determine the size hole you need.

PVC would be cheaper and easier IMO. Looks like some nice fish


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## anonimus (Nov 9, 2012)

cantrell00 said:


> glass-holes.com


well in fact I dont want to make a hole in my tank at this point, I dont have an temporal house for all my fishes, but interesting page indeed!



b3w4r3 said:


> Do you have access to PVC pipe? There are many DIY articles around for constructing an overflow out of PVC pipe only. They are kind of unsightly, and I don't like that you can't see the water in them, but a lot of people have been using them.


I know them, but looks a bit ugly to me, hehe I want to hide the PVC at most possible



b3w4r3 said:


> One potential problem I see with your diagram is there isn't a way to change the height of the skimmer box (the retail unit looks like it has a couple set screws to raise or lower the whole thing).The position of it will determine the water line in the tank, and it's nice to be able to adjust it if needed.


With skimmer box, you mean the "overflow box"? About the screws, I dont draw them in the diagram but the box it will have two, like the ones on the first image



> As far as the holes are concerned, they will be determined by the bulkhead size you use. Make sure you select a large enough bulkhead that is rated higher than your return pump at the current head pressure.


The overflow box should have a bigger output than the return pump? or can be of the same size and controlled with stopcocks?



> Looks like some nice fish


Thanks a lot! the blue ones are my favorites!


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## b3w4r3 (Dec 14, 2012)

By skimmer box I'm talking about the part that hangs in the tank and skims water from the surface. If you plan to use the set screws then that should work to allow you to adjust the water level.

You can throttle the pump if you need to, but it's best to always make sure the drain can flow more GPH than the pump can move. Here's a quick link I found discussing flow rates of various size bulkheads http://www.wetwebmedia.com/BulkheadFloRateArt.htm


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## jcabage (May 29, 2012)

PVC is probably your best bet here. If you paint it black, you shouldn't have an issue hiding it in a corner. It can be no more unsightly than a canister intake.

The issue with a power outage comes through your return, not your overflow box. You can drill a small hole just under the water level you decide on in your return pipe to alleviate this issue. My biggest concern with external overflows is always when the power comes back on. If the siphon breaks on your overflow, your entire sump volume gets pumped into the floor. I've seen some posts claiming the PVC overflow is reliable - I just like drilled tanks if I'm going to be using a sump.


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## zquattrucci (Apr 25, 2012)

cantrell00 said:


> glass-holes.com


2nd that


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