If I remember right, I got the flex hose at Home Depot. I think it was 1" outer diameter, inner diameter 3/4" ??? I had to stretch/ream the inner diameter a little in order for it to fit over the inlet/outlet nozzles.
Cool Sounds like I should be able to use 1" ID so I can run soft line to and from the UV then plum the rubbed line into a hardline to the return. thanks alot.