How do you make a closed loop?

[Tobman]

Can anyone point me to an article(s) or drawings that discuss the details of a closed loop system?

Do you have to drill holes in the aquarium or can it all be done over the top/edge?

 

[shurley]

http://www.melevsreef.com/closedloop.html

 

[ste6168]

I just made a closed loop sort of like melevs that was posted above, but instead of only two outlets and using a SCWD, i made a clafo manifold with 5 outlets for my 75g.