This partially pertains to the creekbed I'm going to do, but the pipe thing pertains to other water features too. I've done all mine, so far, with the black flex pipe. But I'm thinking about using Schedule 40 PVC for waterfeatures where the water needs to be sent 20', 40' or more, away. The friction loss is close to zilch with PVC. I probably will use a bit of both, if I switch - a little flex and a lot of PVC on the long run. Does anybody have any preferences for their pipe from the pump?