Interesting information. The cheapest I've found Flourite Black Sand is at Doctors Foster and Smith. $17.99 total shipping for 12 bags. The bags themselves cost a little more than other places, but it works out to less in the long run because of the shipping. With the $15 coupon you can find online, it puts the Flourite Black Sand at $22.24 per bag for me. $266.87 seems like a lot of money to put into coal slag (or whatever it is) to cap mineralized soil in the bottom of a fish tank. LOL Especially when there is so many other things I need to get the tank running.
If anybody knows of a cheaper place to purchase, I'm all ears!