Your candy cane coral doesn't need (or want) phyto. It'll take small chopped up pieces of mysis shrimp, or other meaty stuff. Whether or not your feather duster needs it is probably questionable. I wouldn't use it at all, but if nothing else I'd lay off using it until you get your algae issue cleared up. I wouldn't think using it just once would cause a problem... unless you used a ton of it.
How often are you doing water changes? And are you dosing anything for calcium? 520ppm for using RO
with Instant Ocean just isn't right, unless you're adding something else.
Reducing your lighting will definitely help, but if they were only on for 2-3 hours to start with, there's something else fueling it.
When you mentioned you're using a "regular filter", what exactly is that?