Originally Posted by gus1911
When live rock becomes encrusted with coraline algae and the porosity of the rock is no more, how does the rock continue filtering the water? Isn't the microlife now dead? After encrustation, what's the benefit?
The primary benefit of coraline algae is to deter unwanted algae growth. Systems with good coraline growth have less risk of hair and bubble algaes, and generally experience more rapid coral growth. Coraline is an ideal surface for corals to to lay down a base an spread, exactly the opposite reaction that corals have when they encounter hair algae.
Coraline is also an indicator of the overall health of your system.