I run sch 80 for durability. A buddy dropped a rock on his standard bulkhead that was one of the ports for his closed loup. It cracked, and guess what? He lost the whole capacity of the tank. I advised him to use sch 80 bulkheads, but he said they were too expensive. The sch 80 bulkheads are bullet proof! If your worried about the ID then upsize to the next size up. Simple! I have never had a sched 80 fitting, valve, or bulkhead fail, and I have installed a bunch. I don't run much sch 80 pipe, but that may change. The point I'm trying to get across, is that closed loup plumbing is nowhere to cut corners. They are just as imporntant as the tank itself. Drived me bat crazy someone wanting to place their coral collection in a craigslist tank that is 10-15+ years old and wasn't a solid tank when it was new. Jason