increase overflow drain rate?


New member
I have a single hang on overflow box. Amiracle brand I think. It has a single U tube and a Single Drain. I want to add another drain (or bigger one) and second U tube to increase the flow the box can handle. Will I have to widen the teeth on the inside box? Can I just cut away all the teeth and use a screen of some kind? The tank is small so adding a whole second box or even double box is out for me. Any input/insight would be great.


New member
It'll probably better to enlarge the current hole than to add another pipe. Also, larger pipes have greater flow than multiple smaller pipes.

(cause area of a circle is pi R squared)

Also it will cause less headaches than adding a new bulkhead next to the existing one.

I had a home made overflow that I tried multiple drains versus larger single drains, etc.

You might actually be able to keep the same siphon U-tube (the faster water flows though it, the easier it is to keep clear of bubbles.)

I'd leave the teeth and just try one thing at a time, starting with the larger drain. I also sugget this because since there is already a hole in the box, using a file or router (or dremel with the dremel router bit) is much easier than adding another hole.



New member
Update.... so far here is what I did. In order to not modify the acrylic parts at all I added a 2nd U tube since I already had one. The one inch bulkhead in the outside box is handling the extra flow no problem at all. After several days there is no air in either tube. The water level in the inside box is of course a bit lower even after opening the return pump all the way. As long as the U tubes stay clear of air and flowing well I will probably call it good enough.