Southdown ??

[Just2Bad]

Hi, how many of you are using it in their tank for a long time ??? I'm asking cause I saw this thread on RC

http://www.reefcentral.com/vbulletin...hreadid=120951

I have 4 bags of southdown that I want to put in my tank. I did the magnet test in a little scoop of my sand and I got many black things stuck on my magnet and I think I got too many for the little scoop I just tested..

Anyone has already tested is sand ???
What do you think ?? Should I worry about it ???