Well, it seems like forever. Well It's close I guess. I don't think I've had a FW tank in the house in about 15 years. I finally got around to carving up the fishroom and got my first FW tank going. Water's in, circulation and filter running, and should start a fishless cycle this weekend. But thinking down the line...... it has a base of flourite with black Carib-Sea "tahitian moon" sand over it. For this one tank, the black substrate just looks awesome. But it's been so long since I've dealt with FW fis issues that I have what I hope isn't a lame question: This substrate looks and feels like a black silica-based sand. Does anyone think it would cause issues with a few cory cats rooting around in it?