Welcome fellow return to reefer after many years out
Lots of stuff has changed for us old school like using live rock to avoid start-up issues.
Did you cure your rock and was it dry rock and what sand did you use? Because I would say with a new tank with uncured rock you are pretty much guaranteed to get a bloom of some sort no matter what you do due to silicates and you kind of have to accept it and just use good maintenance to move through it. Things like UV or getting your nutrients to zero will help but they will not stop it overnight in a new tank especially if your already into it you need to get it down to a point where its in balance with your CuC.
If you have algae on your sand then vacuum it, if you have it on your rock then scrub it. Monitor your levels every day, change your socks frequently, skim wet and eventually it will subside on its own if its not down to nutrients. UV is good, I run it but don't exspect it to magically cure algae in the tank that has established itself.