I still don't get it, I have a 50 gallon tank with a single 1/2" return pushing around 300-400gph and all my LPS and soft corals have done very well. Recently put 6 clams in there as well which are all doing just fine. Tanks been running for almost 3 years which no problems. You're still going to get dead spots with a closed loop, but dead spots aren't going to kill your reef. LPS corals don't like lots of flow, you're going to do more harm and good. Plus extra heat, noise, potential leaks, clutter, maintenance, and less space in the stand.
