I walked up to my tank and was greeted by my clowns as usual but I saw my female was shedding something that looked like white powder. I have been dealing with a small case of ich and it has been dying out (looks like the female is the only one that has spots left, and there are like 3 and there small). I just did a water change on Thursday so it can’t be that and the only thing that I dose is reef medic (peroxide salt) I have a 20 gallon cube. Can someone please tell me what is wrong.