Help....No Coraline Algae to Speak Of

[Aquattro]

Personally, I think excessive coralline growth on the rock could interfere with it's capacity to filter, due to interference in porosity. This is just a theory I made up, but it makes sense to me. So not having coralline on my rock is good.
I've always tried to not have it, so can't really offer any advice if you want it on purpose