Is this green/brown hair algae or dinoflagellate?

Hi all,

New to reef keeping but not to the hobby. Not sure which algae (or dino) this is. And some assistance please with killing it

Tank is 3 months old. Finished cycling about a month ago. Slowly adding frags and one larger polyp.

Some Info:
Tank: Red Sea Reefer Nano (21 Gallon Display, 8 Gallon Sump)
Water: RO - Params perfect. Zero Ammonia, Nitrite, Nitrate. PH @ 8 (May need to buffer)
Skimmer: Bubble Magus Curve 5 (Huge i know)
Media Reactor: Aqua Top with Phosbond
Light: Halo Deluxe
Salt: Instant Ocean Reef Crystals
Livestock - 1x Lawnmower Blenny, 1x Red Scooter Blenny, 1x Ocellaris, 1x Firefish, 2 Nesserite Snails, 2 Mexican Turbo's

Not Dosing, doing 20% weekly water changes.

I uploaded them to imgur because they are large in size and the forum wouldn't allow the file size.

imgur.com/a/x40uw <- You may have to copy and paste the link

Thanks for taking a look! Very much appreciated.