Installing internal overflow box. Help?

[aggrifin3]

Just wondering if you know location, size, and how many holes I would need to drill for a 40 breeder with approximately 700 ghp.
example http://www.bulkreefsupply.com/cpr-retrofit-overflow-box.html
and is there a style that works better? Box or open back.
Am I able to know location, size and how many holes before I actually buy the box?

Thanks

Art

[Angel<3Nanos]

A 1" bulkhead gives you around 900ish gph. And a 3/4" gives you around 600ish gph. I say drill for 2 of the 3/4" bulkheads. That gives you an extra bulkhead for emergencies. And in the case that you want to have more flow. Jmo

I use boxes.

For my new build I'm using one of these..

http://www.ebay.com/itm/Retrofit-Overflow-Box-by-CPR-ROF12-Surface-Skimmer-Up-to-120-gal-Aquarium-/321211325288?pt=LH_DefaultDomain_0&hash=item4ac9afdb68

[aggrifin3]

Whats the difference in the open back and closed box overflows. Is one more desireable or better than the other to have?

 

Thanks