Is there a relationship between phosphate levels and lateral line disease? The recent study that links the use of some activated carbons to lateral line does not says anything about the phosphate levels in the lignite carbon that was used. I recently experience a reading of 10ppm in my reef aquarium due to overfeeding and for not replacing the GFO as frequent as I used to. Three of my blue tangs (Paracanthurus hepatus) started developing lateral line for no apparent reason, these tangs have been in the same setup for the last 3 years and I have being using pelletized carbon 24/7 with no problems whatsoever. This past weekend a performed a major water change and replace the GFO, I will monitor the phosphate levels and keep you posted if I see any improvement on the fish.