sump box size for return pump?

[Sir Patrick]

Here is a pic of my sump/frag area-

http://i33.photobucket.com/albums/d87/sirpatrick1/fishtank/Picture023-2.jpg

As you can see- there is limited room for a traditional dual bubble trap- 3 chamber - sump. I have decided to put 1 wall, open on the bottom, between the frag rack and the skimmer. I will need to build an open top box, in the back corner, behind the frag rack, to keep the return pump. Dont want sand and such getting sucked up in the pump and clogged.

My question- what dimensions should I make this box??? I would like to make the box large enough to house most 600-900 gph return pumps. From the searches I have come up with, 6x6, and deep enough to go slightly heiger than the frag rack should work, but would like to here some info/opinions from my fellow reefers before I go ahead and order the glass.

Let me know our thoughts and sugestions!

[ReeferRob]

Great question Chris. I would make the walls only as high as they have to be to keep sand out. Mine is about 1-2 taller than my pump, and then I attached gutter guard to help keep any algae or other unwanted crud out of the pump chamber.

On the other edge of the sword keeping the chamber as small as possible but really tall will allow more water volume to be kept in the sump. Also if you loose syphon on the overflow it will only pump that much water into the DT avoiding a big overflow.