Any ideas what this might be? There is some sort of growth on this rock. I’m not sure how good you can see it in the picture but it is a milky white colored layer of something. You can see towards the top that it is growing up away from the rock.
The tank is about a year old and the spot is in low flow area at the back of the tank.
The tank is about a year old and the spot is in low flow area at the back of the tank.