I have a friend that has the same issue too. a small whole in her LF spits a column of stuff out leaving a little pile of debris at the base of the rock.??????????? :thinking:
My tank does this as well. The "strings" look almost exactly like spider webs and are abundant when I am cleaning the tank or the water is disturbed in some way. I think they are trying to capture food with these strings because my bubble coral has the same stringy type stuff come out of it whenever i spot feed it. It comes from these little worm type things that are in the rocks. They look like very small feather dusters with no crowns. Never hurt anything to my knowledge.