What size overflow box?

[MarineGirl411]

Hi everyone,
I wrote the in DIY about the overflow boxes, but no one can quite seem to give me an answer. I am setting up a 40 gallon breeder aquarium. It will have a sump/refugium around 25 gallons. I would like to know how small can I make my overflow box? Is 4X4 too small? Or 3X3? Also, how many inches down should I drill for my bulkhead hole? I have a quiet one 3000. It will have around 3 1/2 ft of head. Running around 600 gph or less. How many inches down, from the surface of the aquarium, should I drill my hole for my bulkhead for the overflow? I hope that makes sense. I will most likely start drilling this weekend. This system will be run on Loc Line for return and CL will contain a sea swirl and loc line. I'd appreciate your thoughts. I am going for a corner overflow box. One that does not go all the way down to the bottom of the aquarium. Just a small corner overflow box is what I prefer. What do you guys think? The Closed Loop will be run by the Sea Swirl and T'd off via Loc Line since it can only handle 850 gph. My other pump I will use for the closed loop will be the quiet one 5,000. What do you all think? I'd apreciate your help.

[culdublvd]

Thy this thread<p>http://www.reefcentral.com/calc/drain.php<p>The minimum linear over flow size, is what you are looking for.

[MarineGirl411]

so 9 inches is what I am getting. That seems to be pretty big. It seems like it's going to take up a lot of room inside my tank. I don't know. I am a little lost now. And they don't tell you how wide it should be either. Oye madre.

[MarineGirl411]

So what GPH do you recommend running through the sump then to provide efficient skimming?

[calvin415]

MarineGirl, what 9 inches means that the overflow box needs to have a linear length of 9 inches... Meaning that if it's centered on the back wall (3 sided) you could get away with a 3x3 box (3x3"= 9"). If it's in a corner (2 sided) you'd need a 4.5x4.5 box (2x4.5"=9").

Hope that helps.

Of course that's only if you want a box, you could do an overflow that's centered on the back wall and is 7" long and stick out 1" (7"+1"+1"=9")

[MarineGirl411]

ok thank you. I understand now. =)