Had a really bad outbreak of dictyota (pretty sure that’s what it is). Would brush it off rocks and scoop it out with a fish net. In 4 or 5 days was back with a vengeance. Was thinking about just giving up. After researching here, I got 2 emerald crabs and starting dosing vibrant. Miraculously it’s disappearing. So was it the crab, the Vibrant or both? Guess I’ll never know. Whatever it was I’m happy with everything again. You can see a small piece of it in pic.