This sounds like a Shimek advice rerun here. You don't need strontium, but, you do need a trace of iodine in the system. A TRACE, not an overload. You may get a trace of iodine with some foods, not with all of them. People having trouble keeping shrimp alive for a long term period must think this thru. The molt can not happen or be achieved with proper shell replacement if there is too much or too little. That also applies to metals. Too much is an inhibitor. Just to give you what a trace amount is, if you take 1 small drop of lugols iodine and put that one small drop in 100 gallons of salt water, that is a trace amount. That will more than supply a heavily stocked mature reef tank. A newer, less stocked tank needs much less and probably will get enough with regular water changes. By regular, that means at least 10% once a month.