Nice job! If you will put a few wooden sticks mixed with the pvc you can locate them with your electronics a lot easier. Just my

+1 to what he said

It is too late to put wood on them now, But I am going to find a spot,throw down a buoy, drop the condos and then mark it on my Garmin
Maybe the Garmin will pick up the cinder blocks on 2 of them

It's not to late till they are on the bottom of the lake. You can use wire ties are screws to secure pieces of wood to your pvc before your lower them down. Good luck!

In my experience when it comes to using PVC for condos it`s best to line up two GOOD points for reference on the land first before you drop them.

Why not just cut a broom handle or get some wooden dowels to make the PVC a little more solid. I think the thin walled PVC is what makes it hard to get returns.