I have used both, with the PVC, you will want to sand it, or I bead blasted mine. The reason is PVC is very slick, sanding it allows the algae to attach allot faster. I wasn't sure when I was building my structure, so I sanded one and didn't sand one, put them both in the water the sane day only a.few 100 yards apart. Wanted to see the results, went back a week later, sanded pvc was covered, un sanded had little to no algae on it.