[Eugooglizer]

Does anyone know what type of algae this is? It is red, grows in circles, and grows very slow. It is incredibly hard to scrape off the glass compared to other algae's. It looks cool on rocks but not on the glass and I'm trying to see if there is a different way to get rid of it. Bristlenose plecos do not eat it. Excuse the stirred up water picture was taken during water change.

 

[noddy]

This is the first time I have seen anyone else with this issue. I had it in a tank that I eventually had to tear down and get rid of. I also haven't used the filters or heater that was in the tank again. It started out as a red spot on a piece of dead coral I stupidly brought back from the Caribbean. It completely took over an entire 5', 120g tank. All the rocks that were in the tank went out into the garden.
Not sure how it happened but I have one large rock in my 210g tank that I just noticed had a few of the red spots on it this week (this rock has been in this tank for two years). Straight into the garden it went. As far as I can tell, it's coraline algae and I have no idea how to get rid of it beyond muriatic acid.
Good luck.

 

[Mr Chromedome]

As stated, it is a coraline algae, which are more common in SW, so when I started getting it I asked a person who was knowledgeable in SW. He said it is probably encouraged by excess phosphorus, and my experience has been that mild acids do not affect it, chlorine bleach does not affect it, and hydrogen peroxide does not appear to have any effect. Scrubbing will wear you out by the time you get a few small spots. I found the best way to remove it from glass is a razor blade. It tends to come off in a solid piece when done this way, but eventually it will return once a surface has been contaminated. Fortunately, it can take a very long time to reach major infestation again.