A friend of mine is technically on a different industry (water for semiconductor use) but he said that UV light is not really that effective, especially if a bi

A friend of mine is technically on a different industry (water for semiconductor use) but he said that UV light is not really that effective, especially if a biofilm has grown. Even if everything works correctly and the setup killed stuff, it doesn't remove their corpses (only filtration can do that). Edit: however it seems that the machines were maintained, so it might not be about this specifically.