What is this algae and how do I treat it? Rhodoliths?

[glb]

This algae showed up in my tank a few months ago and I can’t identify it or get rid of it. My nitrates and phosphates are 2ppm and 0.03ppm. On the sand it’s in little balls, with the core being a piece of sand or rock. On the rocks, it’s encrusted and almost impossible to remove. The corals are fine so far. I studied online and the only thing that seemed close was Rhodoliths, which I’ve never heard of.

My tank is a 40g mixed reef up and running for 6 years. The only thing that’s gone wrong lately is a drop in alk to the 7’s due to a problem with my dosing pump. I have two emeralds in the tank but they’re not touching it. I like to treat problems the natural way rather than chemically. Any help is greatly appreciated!!

 

[X-37B]

Looks like gha. Natural method, get a sea hare and rehome it once the algae is gone.

 

[Mohammad.ki]

are you using a filltered water this grass algae shown when normal water added to the tank and try to lower the light abit and if you have white light in the room turn it off make the room dark for 3 days it will reduce the algea from the tank and sun light will make algea also avoid it also you can get a fish that eat algea like tomini tang it will clean your tank

 

[glb]

are you using a filltered water this grass algae shown when normal water added to the tank and try to lower the light abit and if you have white light in the room turn it off make the room dark for 3 days it will reduce the algea from the tank and sun light will make algea also avoid it also you can get a fish that eat algea like tomini tang it will clean your tank

Thanks. I think my RODI filters need to be changed. That’s the only thing that’s changed in the tank. Appreciate the help!