PVC is difficult due to being round for sure, sonar pings goes down, and really doesn't have a flat surface to bounce back. So get's minimum return. Then when it gets a build up of alga, it has something to absorb the ping even more, making it that much harder.
We fish 3 different lakes, and it seems that one lake that has no timber in the lake. So, the Bamboo, and PVC due a much better job of holding fish on this lake than the other two that has a lot of timber in them. Seems like, given the choice, crappie will stick to what they have seem most. Lake with no natural cover, will hang on anything available. Just my thinking.
keith