overflow/drain options for 3600gph


New member
I am beginning to plan out my overflow system so I can order my tank. I will be running a reeflo for my return. 4 1" returns. but what dimensions should I make the overflow box? I want to use 3 1.5" drains using the HGB to silence it, I was thinking 18"x3" for the box is this enough?


In Memoriam
beans failsafe with a coast to coast works like a charm.....running it with my dart and its flawless...:red house: page 8 i beleive has some photos of it...


New member
If you want to flow that much water, use full siphon, not a gizmatchy on a stockman or durso style drain pipe. BeanAnimal's S&FOS system renders such things obsolete, in terms of performance, adjustability, and after initial setup, is set it and forget it. You are already planning three holes, so make them work for you, rather than you work on them.

An overflow box that size, at these flow rates, will pull more subsurface water than surface water. Organics collect at air/water interfaces, (why a skimmer works), so you want the "surface water" out of the tank as quickly as possible. The longer the overflow or "weir" the thinner the sheet of water "overflowing", the quicker the organics get to the sump for processing.

4 - 1" returns is roughly equal to 1 - 1.5" pipe as far as area is concerned, however, the associated fittings pipe, and such, will add additional friction loss to the equation, reducing your flow rate.

The question you need to ask yourself at this point is: Do I want something that will get me by, that will work? Or do I want something that will work well?




New member
not sure that I want to have a full length overflow, 30"x 4" or 30"x 6" sounds better to me. I think I will experiment with beans' overflow.


New member
as a guide using RC Overflow calculator, the linear length for 3600gph should be 54". That gives about 1/4" of water over the lip.

Can also use Bazins formula to work out the height of water over the lip of the overflow based on length and GPH.
http://www.aquatext.com/calcs/weir flow.htm

RDO has a calculator (Excel Spreadsheet) for a notched weir that you can play with, just use one notch. see here

Also suggest looking into something other that a Durso or type that draws air along with water. I'm running Dursos and though they themselves are quiet, the gurgling in the drain pipes and the sump is a little bothersome. Sure Beans' work but a classic Herbie works well also.