Wheaties- Your edge looks great! I know short periods can be used but don't think we are sure that too much light is the issue here. Now that we hear about the natural sunlight I suspect that. I agree with Hotrod's approach. Small change... Wait and see. A little algae is not bad. Also Wheaties; I would love to know why you run a 4 hour day. Is your bulb too bright for more hours?