I have a mature (3 year old) reef and about a week ago this green algae started forming on my sand and small bits on my rock. Not sure what it is or how to get rid of it. My nutrients are pretty consistent around 5-10ppm nitrate and 0.05ppm phosphate. I have pretty decent flow, enough that any more will irritate my euphyllia on lower parts of my rock. I have various snails, hermit crabs, and tangs which aren’t interested. Im not sure what it is and I’m afraid to use vibrant because I’ve heard it kills chaeto and I have a large piece of healthy chaeto I don’t want to lose. It’s formed behind or underneath coral so I can’t just remove it mechanically, or at least easily. Any advice?