I also saw a pic of the State of Mississippi using these but made out of double hole blocks with maybe 20 risers coming out of them. Do you find that the pipe stays in the concrete OK, or are the sides too slick and let it slip out? Just wondering if I should drive a nail or something into the pipe to give the concrete something to grip to? Have you actually found bass to hang out on these? We made some large PVC pipe tree structures a few years ago but so far have not had much luck with the bass being interested.
Regarding "roughing them up to better allow algae to grow"... I read a suggestion someplace about just tying the pipes in a bundle, and dragging them behind a truck on a rough road. Sure sounds like it would roughen up the pipes. richg99
Love the idea. Just put two structures out using PVC and a couple old water hoses. Holds fish but you guessed it...you can hang a plastic worm in it due to the water hoses. Thought the hoses would float around more but I'll use pipe next time.