ahem... to respond to YOUR question, you can mix any perlite with OF and i'd definitely recommend doing so. However, mg perlite is amended with time release fertilizer, and I'd make sure to check because I think scott's perlite is as well, but just check. Now, the fact that both of those companies are owned by Monsanto is a good reason to just go to home depot and get a giant bag of horticultural perlite from the garden section instead of either of those two. And, if you get the urge to, you can set up a ton of hempy buckets with perlite; and its reusable so you should be set on perlite for a good while. and its cheap. and i'm baked.
