Alastair said:Yeah 2 hours earlier is good, you may not need to up the rate of co2 if it's coming on a few hours earlier. Just see what works best.
Surface film can be caused by a few things. Mine was caused by incorrect co2 causing my plants to become sick and cause this film. Once sorted it cleared. The only other time I had it was when I rescaped.
dazza said:Bought some liquid carbon today and upped the co2 slightly.
Think 2ml of carbon daily would sort it out?