I observed some of this at a local pool store being sold in 1 and 5-lb buckets fairly cheaply.
Couple of google searches revealed this is a useful lewis acid, and relatively safe if accidentally consumed in small quantities (not that you would
want to), due to its use in swimming pools. One site even claimed it as a "strong lewis aicd". I can't imagine it would be too difficult to dehydrate
a bunch of this in the oven