HF 110lb Blaster questions

It says in big bold letters DO NOT USE SAND. It don't work real good, either. I tried. Any moisture in the air at all and the sand will cake up and clog the blaster. I used aluminum oxide. Got it at HF when I got my blaster. Make sure you lay out a tarp on the ground to catch the excess. You can strain it with a screen and reuse it. I got two 40 pound boxes to blast the under side of my 65 Coronet. I still have an unopened 40 pound container left. Like I said, I would not use sand. I will not again. lol