Left is chaeto, right is some sort of algae that grows on my rocks. Very similar to chaeto but thinner and seems to grow attached to the rock. Can't seem to find anything on Google matching it's description. Definitely not hair algae and doesn't have fronds
Can’t tell you exactly what type I t is but similar algae blooms are an indication of some imbalance within the water column. It’s a natural response to excess nutrient levels but these types of responses can reck havoc in an enclosed environment like an aquarium. I suggest checking numbers to see what might be causing the bloom. Hopefully someone else can ID the type of algae. Good luck.