I use Seachem Reef Salt. However, I was fortunate to take a behind the scenes tour of the Georgia Aquarium last week. They have a 6 million gallon "ocean" tank in addtion to a ~170,000 gallon reef tank. Guess which salt they use?
Yep. You guessed it.
Good, old fashioned -- IO.
I saw pallets and pallets of HUGE bags of the stuff.
I think I will switch back