Newbie reefer here. Recently, I've been battling a brown-ish growth in my sand bed. I suspect it's cyano due to the presence of small tendrils, but its brown so could it be diatoms?
Its a 75G, currently stocked with 2 ocellaris clowns, 1 royal gramma, 1 firefish, 1 starry blenny, and 1 pajama...