cedar creek farms said:we used four and five inch on different ones just put a cap on one end then a elbow with a screw in cap on other end. Predrill holes stick rope through holes bring out to end of pipe and tie a knot in the end that will stay in pipe so it doesn't slide back through. Leave the rope sticking inside the pipe aways then it will pick up chemicals up when the tube gets low. If need more info let me know