Types of vermiculite.
Can I use pool base vermiculite on my garden soil as an amendment?
Certified GKH Gardening Expert
From my research, it doesn't appear to be any different than that of horticultural grade vermiculite. In fact, I have read sources that stated that gardeners get price gouged, and that it was just the same grade stuff. I would always recommend reading to see what it is the bag before you buy. Otherwise, There doesn't appear to be any reason not to use it.