Silica is the right stuff. Just wish I could find course stuff locally.

Thanks... True, This sand is very fine. It would be better with with a more course sand.

A pool supply store would have pool filter sand. That is reputed to be good for CP's. So is sand-blasting sand. I've been using "play sand" from the building materials department of Home Depot. I have no discernible problems. As with all soil media, rinse the sand first.

Sandblasting with silica is quickly becoming illegal all over the US. It's been illegal here for years. Pool supply stores is the only silica sand source I know of around here. I haven't tried play sand yet. Rinsing the media is always a good idea when it comes to CPs. I even rinse the peat until the water is almost clear.