Closed loop isn't a bad idea for some added flow - especially since it's hard to get flow low in the tank/under rock work etc. with some of the standard power heads. I would, however, suggest what PDXmonkeyboy said and add another hole for a feed line higher on the back of the tank. Also, would not suggest using reactors in this loop as they are sort of incompatible with the high flow you are looking for in the CL setup... unless you want to split off a side loop with more restricted flow but that would be a fair amount of extra plumbing. Probably better to do the reactors off of the main return using a manifold setup. Just my 2 cents... Good luck!