what type of sand to use?

No one has talked about fine grain sand. Just go a janitorial supply place and buy a 50 LB bag of silicone sand (used in hotel lobby ash trays). Cheap, about $10-$15 a bag. I used it with Bright Star Audio Big Rocks when I had them. Good listening, Jeff

I bought a the suggested white sand for playground use. Then I went to the 12 o'clock mass and had the priest bless it when I went up to receive communion. My wife then left me when we got home, finally I was able to listen to music in peace. I hope she doesn't come back!

goldenear,let's try to keep religion out of the conversation and stick with tried and true facts,like my Alien Sand.Only 2 pounds left,get some while you still can.

I bought a 50 lb. bag of playbox sand for a few bucks. Used a frypan on the stove and dried it. (better than sun because the sand gets really dry, drier that humidity of air..) then as it is still warm put it in Ziplock bags. So the sand is very dry and ready for use. I packed three large steel racks with this stuff. i did not need the alien area 51 sand, as i AM a alien. That stuff is sucky... It is from a planet NO ONE would get sand from unless they were YB'Gzains.. and we all know what morons they are. Proof is: why did they crash? huh? tell me... morons...
(At least I just ran out of frit-48 gas... )

Silica sand it what you are looking for.

Should be fairly easy to find, as it's used for sand blasting (bone dry if stored properly and inexpensive).

Wear a breathing mask/cloth when pouring it as the dust is not something you want to inhail.

Perform the task outdoors.

Research silica sand for your application in order to judge the previous sandbox responses to your query.