Well if you must change your lights, just skip a light cycle and start the new after the dark time.

I am not used to C temps, but I don't think those are that bad. What is your hydro temp? That should be close to an average/constant temp.
WashougalWonder Reviewed by WashougalWonder on . Cold night time temps Hi all, Just a quick question for you experienced indoor gardeners.... This is my first hydro grow and I'm getting big temp differeces between day and night (10degC min and 24degC max last night) as it's turned cold again over here. I was wondering whether it is ok to change my light cycle from being on during the day to being on at night? I have an oil filled rad on at night but it doesn't seem to make much of a difference (seems to raise night temps by around 5-6 degreesC). If it is ok to Rating: 5