I usually use fairly large pumps so have gotten use to male or female pipe threads as a pump exit, can not even remember last time I used a pump that came with a hose barb other than a power head. The purpose of larger pipe is less restriction/friction more flow. You can use barb adapters to up size vinyl hose and get the same effect. Plus look at the inside diameter of 1/2" or 3/4" hose barb versus the inside diameter of a 1/2" or 3/4" PVC pipe. A hose barb goes inside your vinyl pipe therefore is smaller than the pipe and thereby greatly reducing the flow. A PVC fitting goes over pipe and therefore does not greatly restrict the flow. Plus with PVC pipe you can put in unions and ball valves to disconnect equipment. You can use them with vinyl pipe by using a lot of restrictive fitting, or by going to larger hose to cut down on friction, but you will always have to go at least one size larger than PVC pipe to get the same flow. There in the real world (continental U.S.) flexible PVC pipe should be readily available and it uses all standard PVC fittings and glue. Remember electricity and pumps are expensive so should be used in the most effective way reasonably possible. Remember if your feeding your pump from a refugium or sump you must put in anti siphon holes in your return lines to keep from possibly overflowing your sump during a power outage. If you run your return very deep in your tank your talking water on your spouses floor during a power outage, and coral nor fish live well out of water. Anti siphon holes are just holes in your return lines that are usually just below the surface of the water that stop a siphon when the water level drops to that level. My ISP was down most of this weekend so I did not get to post earlier. Sorry. Sump/Refugium looks great! You are really getting there. Sure beats dreaming and talking, huh.