There are alot of ways to accomplish this, but the simpliest way to explain it is... You need an overflow, a CPR for example. Use either flexible tubing to pipe down to your refug, I used 3/4" pvc but I didnt like it, and switched to 1" flexible tubing, home depot style.
After you run through your refug, depending on how you have it setup, you'll need to return the water. I used some acrylic pieces purchased from home depot made an overflow to a small space in the side of the refug where the water spilled over, and the pump sent it back up to the tank. I used a ball valve to adjust the flow of water returning back to the main tank. I'm not sure if this was the best idea, but it works great for me.
I used a Mag 7 pump, which is a tad noisy, but works great. If you're using a rubbermaid, it'll be a bit less noisy.... hopefully.
I plumbed up from the ball valve using flexible tubing again, into a "T" and used some of those snap together, flexible pieces that you can get online or any LFS to spread the water to 2 different locations in the tank. Wish I had my digital camera, i'd show ya.
Anyways, i'm sure you'll get many other suggestions, and hopefully some pics to go along with it.. HTH..
