Wow, I checked my tanks today and discovered the water to be very cloudy and the skimmer to be overflowing. Inspecting further I found at least 50 large bristleworms which had climbed up out of the sand and on to the tops of my halimeda bed squirting the thick white stuff out of their ends. It was rather disgusting to say the least. So I'm wondering what they were doing. I changed the water and the fish look fine so I'm not that worried.