Tiny hairy red spots

[szyker]

Hello, there is plenty of tiny red hairy spots on my rock and I have no idea what is that.

Description:
Tiny red spots on the rock. It looks like small hairy algae, but never grows higher than 2mm. In natural light its red, in blue more purple or dark red. It's in random spots all over rock. It doesn't appear on the sand. It doesn't spread rapidly but I see more and more spots of it. It's rather hard to scrape it from rock, harder than hair algae.

What it's not imo:
- it's not cyano. Cyano is super easy to get of the rock, this one attaches rather strong.
- it's not diatoms.
- it's not dino as they are mostly rusty colour like and also easily comes off.

The tank itself:
11 months, very stable for 4 months already. NO3 around 2ppm, PO4 0-0.08. I have some hair algae on the rock which consume PO4 thats why sometimes it reads 0. The rest params are in check and very stable. Corals, anemones, fish and other organism are in very good conditions. there is plenty of pods and other small life.

 

[EnterName]

Is the hair really limited to the red spots?

To me it just looks like coralline algae on those images, but I might be missing something.

The hair might just be a different algae type that's growing on top of your rocks and doesn't necessarily cause trouble if it stays small and isn't really visible.

Coralline algae is expected and welcome in a reef tank of that age. It's showing that the ugly phase which previously caused diatoms and then green hair algae comes to an end. It's also what is giving reef rocks their distinctive color.