I have a new tank to set up. I sent out my husband last night to buy a bag of blasting sand, having heard that it's nice to use as a substrate. I got him to pick up the 88lb bag, as it was only $10. As I was pouring it into some buckets to start rinsing it last night, I noticed the back of the bag said that it contains up to .2% nickle, and has a warning about possibly carcinogen !! Is this stuff really safe to use in an aquarium ?