What is this black stuff on corals?

[chase thompson]

A few weeks ago my phosphates went up. A green algae covering the glass came from this needed daily scraping. Very tough to remove, I couldn’t use the magnet cleaner not enough strength. I had to use a manual scraper. No problem just been feeding less. When I scrape it, the green algae floated around till it got sucked up.

About 3 days ago…
Now there’s less green algae and a brownish black colored (algae?) appeared on the glass. Much easier to remove with magnetic scraper unlike the green algae.

Again the brown/black algae floats around till it gets sucked up. Did the algae get caught by the Xenia and snow day pipe organ coral? Or is this a disease? They do not look happy at all! Each polyp the has the goop on it is closed.

 

[CoralB]

It’s hard to tell from your pictures but what what your saying it could be Black Sponge . I’ve been dealing with it for about a year . Is this in the lower picture to the left ?