Yes pool filter sand.

When I filled it I accidently got alot of sand in the center pipe at first. So I pulled it up and made sure I cleared it. then in order to get it back down into the first half bag of sand, I had to then spray with a hose to move the sand out of the way. Then I covered the pipe with a sock before continuing to fill. I have not tried the rinse thing before going back to filter. I'll try that and see how it works. Thanks!