Not sure to be honest, But SBB corals made a big post about how all of his tanks were crashing and months of ICP testing all his water sources in and out and his tanks he narrowed it down to believe its the salt, swapped salts to RS BB like I did and saw instant results.Maybe these so-called iron issues in the Tropic Marin are only affecting people that are doing normal water changes on a weekly or biweekly basis of a percentage of 10% or more. But not affecting the people that are using it on an auto dosing system doing daily water changes of a very small percent the iron is not affecting anything dissipating out faster than it could build up.