In the sand box

Inner tubes, elastomer layers, pucks, springs, carbon fiber shelfs, sophisticated integrated isolation platforms (Silent Running Audio), metal cones, wood cones, granite slabs… but not sand, moss, alge, dirt or gravel.

I am using soft sponge hockey pucks, and that has stopped all vibrations that I am able to record? 

Sand works very well when used with a quality shelf.  You should use play sand.  It's very dry and has been filtered.  Sand will absorb moisture so overtime you will need to replace the sand.  That's not really a problem since it's dirt cheap, but it can get messy.

You are correct, it was play sand they used, not beach sand. 

Just when I think people in this hobby couldn't get sillier...