what is combi san for?

[William Kao]

Hello,
I was told by the guy who takes care of my fish tank to add Combi San into
the fish tank weekly. I have no idea what it is for. All he said is it's
good for your tank. I am afraid I'm adding something I don't really need to
add. Could someone help me to understand why I need to add it? On the
label, all it says is minor trace elements. What are they good for? Which
kind of coral will benefit from it? I typed up the whole set up at
http://www.coralreeftank.com. Please help me..

Thanks,
William
http://www.coralreeftank.com