Both schedule 80 and sch 40 parts work for the Red Sea tanks. Most people use sch 40 pipe and sch 80 fittings because the fittings are grey and not white. The advantage to sch 40 is that if you need an extra piece, you can usually just go to the local hardware store and buy it. Make sure you get the 1” to 3/4” mpt adapter if you are hard plumbing your return and using 1” pipe from the pump.
Thanks, that really makes thing easier. I'd like to find out what red they used as to mimic the parts for aesthetics. My sump has a couple spots where the white paint got torn and I'm planning on touching them up with Killz (White). Nothing major and at the bottom. The gray Sch. 80 doesn't look bad but for the sump area I'd like to retain the red and white apppearance. The rest is going to be in my basement and doesn't matter to me. My return is 3/4" so the NPT shouldn't be necessary. I need to put T's off the return and drain out the back of the stand to my sump.