Nice zoas. That algae on the first shot, is that the first you've seen of it there? I only ask I as I had a bryopsis issue for a bit and I found a method that works well for it. If it is byropsis then taking using magnesium can get rid of it with little direct effect on your corals. Just get a syringe and apply the magnesium directly to the byropsis every day and it will not come back at all. The raised mag has not had any negative effects yet for myself or any other reefer I know that has done this.
Bryopsis:
P.S. I am pretty sure my bryopsis was a result of me not dipping a new rock AND using a new salt that apparently had quite a bit of phosphate in it...