Which algae is this?

Some background first: my tank is around 5.5 months old, has gone through a couple of diatom blooms, so I'm positive it is fully cycled. I've only recently started seeing these hard red spots, first on my powerhead and then now on the rest of the live rock. I want to positively ID whether it's coraline algae or something else (don't think it's cyano), so any help is appreciated.

 

looks like coraline
see if u can scratch it off...if there is white calcium behind it then its coraline....if not its just hard cyno

 

Looks like coraline to me.

~Will.

 

Sigh..it's cyano....wiped it right off and slimey.....time to check phosphates...

 

Cyano is actually a bacteria, not an algae, and can be introduced through a number of varying contributing factors. Elevated phosphates and nitrates, insufficient water flow to certain areas of a tank(dead spots) and lighting can bring on a cyano outbreak.
Water changes, increased water flow, reduction of nutrients, new or old bulbs and kelvin of bulbs can be attributed to cyano, where replacing/reconfiguring of bulb coloration scheme may correct this issue, as well as other nuisance photosynthetic plant blooms, such as with derbesia and bryopsis!
Sea Urchins, Sea Hares, certain fish species(Tangs, Blennies, Foxface for example) may help as well, however, the best solution to the problem is to maintain low nutrient levels and sufficient water flow to all parts of your aquarium.

 

Just to be precise, it is a bacteria with some algae like characteristics.

 

Thanks....any specific K rated bulbs I should try (10K, 420nm, 460nm, etc.)? Might go for a tang after all then.

 

who said it was algae LOL

 

Bulb colors towards the red end of the spectrum are more efficient at producing nuisance algae than at the blue/purple end of the spectrum.

 

Estee...What is your current lighting? Also water perimeters