Metal debris in my tank????

[Fishingandreefing]

So I am in the process of setting up my next build so I ran a magnet through the old sand that I cleaned and soaked for awhile. I found some metal debris? that attached to the magnet.

Then I was curious why my corals always die in my 120, so i ran through the sandbed with the same magnet and found a small piece of rock that was magnetic? I did read that some black sands are magnetic so I guess so does rocks then

My biggest concern is, am I safe to use those sand and what the best course of action for my 120? Icp testing?

 

[Fishingandreefing]

Bump

 

[Backreefing]

I would use another sand , but I’m not a expert here . I have had rust in my aquarium without any problems . But I’d never advice it .