Sizing overflow baffles and drain holes

[marjimbo]

Hi! Can anyone help me with some sources of info on sizing holes for drilling the tank for overflow and return, suggested piping sizes and dimensions for the overflow baffles required in the tank.

I'm planning a 125 gal. setup with a basement sump. I'd like to have flow rates in the 800 - 1000 gph area from each of 2 overflows, with separate plumbing circuits for each one, one going to the sump and one with an inline pump returning straight back to a manifold in the tank (instead of using power heads).

I've spent some time searching the web and can't seem to find any info on this.
Thanks

 

[melanotaenia1]

you would need a 3/4-1" bulkhead fitting to attain that type of flow, and remember that holes for bulkheads usually have to be drilled a little larger than the bulkhead itself.

Is the tank glass or acrylic? If it is acrylic, it would be much easier to drill these holes........

 

[marjimbo]

Thanks for the comments. My tank will be glass, but I'm going to get the holes drilled by the manufacturer. I also need some info on sizing the baffle to get the required spill over flow.

Does anyone know of some literature on this??

 

[ChrisRD]

If you're planning on getting upwards of 1000 GPH into each drain, definitely use 1.5" drains.

As for the size of the overflows - for a 1000 GPH design I would probably use about 15" (linear) total for all sides (for each unit), although this could vary based on how wide/spaced you make the teeth.

For example - a three sided box that was 8" wide and has 3.5" side walls = 3.5"+3.5"+8" = 15" should work. How you work the particular dimensions out is a preference thing...

HTH

 

[ChrisRD]

I'll move this to the DIY Forum so you can get some better feedback...

 

[Anonymous]

I have a 125 g, two return pumps rated at 1500 gph each. They sit about 4' below their outlet in the tank. My two overflows are 1.25", and *barely* handle all the flow. The two corner overflows have 12" of linear space each and handle the flow.

 

[marjimbo]

Thanks to all of you for your input - some good information there.