Sump Tank help
I am setting up a 72 gallon saltwater tank, I want live rock, fish, corals, the whole deal. I origionally was going to do a canister filter, but I hear thats not the best route to go, true? Anyways, I have been doing a lot of reasearch on sumps, and I think i understand how they work, basically its a tank your overflow box drains into, then gets sucked back up the otherside by a pump, but what is in the middle? do i need a carbon filter? bio balls? should I run a hang on filter on the back of my sump tank? Just looking for some help, Thanks guys.
Also, it seems like the sump tank would just overflow, how do you make sure your pumping water in and out at the same rate?