At first I thought this was coralline algae, but after reading more, I get the impression that CA is just your standard algae types... The green coating on this rock is thick and fairly hard (and not slimy at all). There is a spot where some cracked off from that is around 1/8 of an inch thick. I assume it is not a bad thing, but it does appear like it could grow over the entire rock, eliminating the benifit of porous rocks and lowering the amount of algae in the tank.
Is this anything to worry about?
Is this anything to worry about?
