Types of vermiculite.
Can I use pool base vermiculite on my garden soil as an amendment?
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.