Recently.I had to change my return plumbing in both tank from clogging,squid failure,cheap LFS return nozzle.I've realized the benefits of oversized plumbing for a while so now i could finally add it.It works on a simple process that can be tested easily by blowing into a cofee-stirrer(its pretty hard to blow thru)then blowing thru a McDonalds straw(easy to blow through).Basically by using oversize plumbing,you reduce the friction in the plumbing and therefore reduce the pressure at the pump.The results in my case were astounding.In my low-flow tank i went from 5/8 ID to 3/4"ID plumbing and changed my cheap LFS return nozzle to 1" elbows that were reduced down to 3/4" at the end and left unglued to redirect the nozzle-elbow.The flow i gained was incredible and HOB overflow had to be modified to accept it.When my squid failed,I changed from 3/4" plumbing to 1" and used a T instead of the squid.All i can say is ,my return pump pumped so fast i could not believe the difference.I had to add another U-tube to HOB overflow for it to keep up.So if your return pump has a 3/4" return nozzle,go with 1"plumbing,a 5/8" return pump,use 3/4".You reduce as close to the pump as possible and at the return nozzles/PVC elbows.Another advantage of an oversize return nozzle/PVC elbow is that it decreases velocity but increases flow.Most corals IME dont like to be blasted.Just thought i'd share my recent upgrade with my plumbing and the results i received