I have had my reef tank since 2004. I have dealt with many algae issues and beat hair algae bryopsis and this strange black turf algae.
Never have I treated with chemicals or dosing. Changing the spectrum of the bulbs has seemed to help and now I am running all led so I don't have the temperature swings.
You may just have a cycle with algae from things dying in live rock. If you have a sump put some piece in there for awhile and it will break off and go away.
Also siphon as much out by hand and if you are adding phytoplankton stop...