Schedule 80 is for high pressure water systems and seems like a waste of money for fish tanks. Just my 2 cents. I have literally plumbed hundreds of feet of of pipe over the years and never used Schedule 80 for anything. Our pumps never produce enough pressure to warrant the extra expense. Check valves are a waste as well due to the noise and failure rates. A properly designed sump does not need a check valve....wait a minute my might need one...lol. Just kidding. Have a great day all.