Try regular red bricks, but buy the ones with the five round holes in them. Two plastic cable ties were used to secure each brick to the pipe every 8-10 feet for its full length.
They are easier on the hands, hold the pipe closer to the bottom, and are easier to move for adjustments. Because gravity pulls them
underneath the pipe, they are less of a hazard to shins and toes and, if buried some, perhaps less likely to be damaged by winter ice. None have needed replacement here in ten years.
