Here is a weird contraption of mine to break the sand blocks that won't break.
I cut a piece of the top blade and the moving one to shake the sand little at the time.
This will be evolving into a drawer type filter system suspended from the ceiling.

The cover on top is an effort to keep the big clumps in when they get grinded.
I made those wood washer myself :)

Here is Jean-Pierre from Enseignes Herem Inc. preparing petro-bond from a kit.
He buys the oil seperately and save on shipping. The resulting sand is really nice.