Name That Stuff...

[MHG]

So when not zoomed in and just looking at the tank, this looks like some sort of algae type growth. Maybe cyano as I just went though that... But when I scrubbed the head with a stiff brush, none of it comes off.

It glows a little under the blues at night...

 

[Uncle99]

That could be coraline algae, a good sign your ALK, CA and Mag are on target.
In the end, it will cover everything..some love it....some hate it

 

[MHG]

my coraline is quite pink or purple. this is maroon and fuzzy.

 

[reefgeezer]

If it wipes off easily it's just plain old Cyano or Diatoms.

 

[devimik]

I had some red turf algae growing on my rocks and powerheads just like that - couldn't get it off without serious scraping. Decided to just live with it and over time it went away. Perhaps me treating with fluconazole for bryopsis knocked it out, but I seem to remember it just going away over a period of time.

 

[ReefsandGeeks]

I'm not certain what it is, but I've had the same stuff before. It seems it doesn't like being exposed to air. I've also had luck getting rid of it with hydrogen peroxide dips and scrubbing a bit with a tooth brush, OR using vinegar to do the same thing. It's been a while since I've done it, or seen it. It never took over my tank, but was frustrating that it wouldn't just scrub off in the tank. It does seem to glow alot more under blue lights after being exposed to air and almost melts away. I've seen a fluorescent dye like color coming off of it after exposing to air and putting back in the tank.

For what it's worth, it never seemed to bother anything. Just doesn't look good.

 

[MHG]

not worth the effort until its time for the next head cleaning...