Black sand for DSB?

[sumpfinfishe]

Hi Clinton, well a friend of mine brought me back 20lbs of black sand from Costa Rica a few years back. Instead of doing all my research on this stuff, I simply added it to my tank. Then after only a few days I spoke with a buddy of mine who has various degree's with metals. He told me that black sand is volcanic, which even though it's found around some exotic reefs around the world, it is however high in metal content.
The number one being Iron, which mix this metal with SW and you spell big trouble in a small closed system such as a reef tank.
I didn't believe his words until I dropped my cleaning magnet into the sand just to see for myself. Well after I picked up the magnet it was completly covered with metal like shavings all over

So IMO I would stay away from any kind of black sand, even if it says reef safe on the bag, just to be safe

cheers, Rich