i do a complete cleaning every few months when the skimmer looks like it's not functioning at full capacity. coralline usually doesn't grow on my skimmer, but i clean the green algae off. i empty the cup once a week.
I clean my collection cup and the top of the skimmer fromt the reaction tube up, about once every 2 weeks. I have had no reason to clean anything else yet. I just do a quick wipe with a sponge on the rest of the skimmer.
my recommendation is clean whenever and whatever you think it's necessary and that includes the coraline.
Thanks guys I guess my question really related to the Cloralline. I know this is considered good algae. It really has started to build up in my skimmer which hangs on the back of the tank.
