How could I get rid of Grape Macro Algae!

[whatcaneyedo]

Remove the rock and place it in a dark sump or circulating bin of water until the algae dies. In my experience mushrooms can survive longer in the dark than caulerpa. But if you're worried you can always cut some of the mushrooms off of the rock to leave in the tank. That is how I rid most of my tank from that nuisance algae. The last little bit of it I plucked out with tweezers. FYI I don't keep any of that crap anymore. Not even in a refugium. Chaetomorphia and gracillaria are much less invasive.