Is this bryopsis?

His tank is still cycling, currently no livestock.

 

The picture was full zoom from about six inches away. If you click on the window when it pops up, it will open it full size in a separate window. The algae is very fine but definitely looks like a feather or small fern. Right now anything I mess up should be correctable with water changes, so I would rather assume it is byropsis and hit it hard. I appreciate everyone’s advice. I was pretty sure this is what I should do but I’m glad I can get input from people who have been through it.

 

Just a quick update. My Mg was actually at 1200 and not 1400 as I thought last weekend (bought a better test kit). I have been dosing the Tech M since Tuesday and am now at 1500. Some of the bryopsis is now turning white and starting to disintegrate. My fingers are crossed but it appears to be working.