Hmm... so I just went back and looked at the other SS tanks I have, and yup, they look light-tight. I have no idea why I thought they weren't. I bought them when I was just getting started, and I probably didn't know what I was looking at. I thought they wouldn't work, so I've been using the Paterson Super System 4 from the beginning. I feel silly now.... Just glad I didn't actually need the 220 tank - I only do B&W myself, so no kickin' myself too badly!