this is on my underwater light fixture and looks like some sort of egg sack. Lots of starfish, wrasses and 2 clowns as well as cleaner and peppermint shrimp and lots of corals. 37 gallon column tank.
Looks like cyanobacteria to me. How old is the bulb in the fixture?
Tom
less than a month old. It is a replacement from one that was a year old and died. I just did a major cleaning in the tank cleaned sand, rock and glass and got a ton of yuck off. I also got a new fixture that is an LED reef compatible and I have noticed a lot more algae with that light on. so maybe I just have it on for night light and let my other coralife fixture do the job with the underwater LED. Thanks for the info though. I honestly thought it was an egg sack of some kind and didn't want to mess with it if it was. Tossed it out along with all the other junk. clean tank now lol.