You will need to have your water tested to get the PPM of the iron, if you have an excessive amount your softner may not be able to handle the removal and you may need to consider the purchase of a iron filter which looks, acts, installs and cost similar to a softner but goes inline before it. The big box hardware stores may not carry these but your smaller ones should a well or water specialty place will. Also adding a product called Iron Out to your brine tank will help and you can buy salt with it already in it.