I actually use photoflo all the time with my negs. I don't use a communal lab, though. I add a few drops to my filled tank (I develop 3 120 rolls in one shot) and agitate for 30 seconds. I've never had a problem with a white film - but I'm in NYC. I would follow the suggestions above and try distilled water, and if you can, add the undiluted photo flo straight from the original Kodak container.