Having several issues... First, A 100 gal FOWLR, sump, water params perfect... In this tank I had a powder brown, 2 yellow tangs, a purple tang, a midas blenny, a fiji foxface, 2 pajamas, a flame angel, a coral beauty and 4 cleaner shrimp along with others you'd find in a clean-up crew. Had a problem with ich (obviously from stress of 4 tangs but all but pb were small, between 2-3 inches.) OK, so the ich is 1 thing... Brine shrimp was being soaked in garlic and all were eating like little piggies. Approx 2.5 weeks before "the incident" i noticed a film covering the rocks. a flowy, clear but noticeable film. Guy at LFS tests my water himself, says everything perfect and this film is anaerobic die-off, increase the flow in the tank and it'll go away and will not kill my fish. 2 weeks later, 2 of my fish quit eating. Next day, dead. Everyone else in the tank ate that day... that night. Boom. Next morning, everything but the fiji, the blenny, the 4 cleaner shrimp and 1 yellow tang are dead (again, they all ate that morning). I tested my water after removing bodies, ammonia barely off (b/c of the bodies i assumed) everything else, perfect.) Could it be the ich? Shouldn't kill like that especially since all were actively swimming and eating. Following advice (not of the LFS), I xfer the remaining fish to a 55gal and start medicating for the ich (b/c it still can't possibly be related to this film) and the tank needs to set. The blenny dies that night (likely the stress from move). I used the "all-natural ich attack" i'd found for 2.5 weeks and the ich never fully went away. And in the 100 gal, the film remains to this day despite adding 2 more powerheads to the 2 I'd had in there already b/c i needed "more... more is better". I do have pics of this film I'll try and pull off my camera in the morning. I've since moved the fiji and tang back into 100 gal where the shrimp have resided through it all, and he's doing fine. Still with the occasional spot or 2 of ich but not rubbing on anything. Today I, against my better judgement, added a couple newbies. Still having doubts about this film though. It's not killed the foxface yet, but they're really hardy anyway. Any thoughts?