I have 2 snails and no hermit crabs in a 270G and previously in a 300G and never had a hair algae problem ... too many nutrients and detritus buildup has always been my guess as far as hair algae goes ... my cousin in JA had a outdoor saltwater pond and huge hair algae problems and he had natural sunlight so I am disinclined to think spectrum alone contributed to it although it may be a contributing factor. The only nuissance algae I have had is valonia and I have no clue how I got it but it never got to plague proportions ( would find one behind a rock or something if I was fooling around in the tank
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