Cold night time temps

[greengrassuk]

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 do this, how would you recommend I do it? I thought it might be possible to put the light on 30hr and then back onto an 18/6 cycle.
My plants are 16 days old and grown hydroponically using a 250W HID.
Thanks for any advice you may have

greengrassuk Reviewed by greengrassuk on 03-31-2010. 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

[WashougalWonder]

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.

[greengrassuk]

Hi WashougalWonder
Thanks for your reply. Just checked my iast 24hrs min and max temps, 8degC and 20degC which equates to 46degF and 68degF. Checked my hydro temp (daytime) which is 21degC or 70degF will get up early to check night time temp but I guess it will be much lower...
If the fluid temp is kept fairly constant (perhaps with an aquarium heater?) is the air temp less critical?
The reason I ask is the plant nearest the intake duct has leaves which curl down and also has some yellow/gold speckles whereas the other is looking really well. I want to understand why this is happening to only one plant. pH is constant at 5.8, EC is 0.7, both plants fed with canna-start at a mix of 1:250 (4ml/l) as recommended on bottle, fluid level approx 10mm below baskets. 16 days old Kaya47 grown from seed in root-rite cubes supported with geolite expanded clay balls.

Being new to indoor gardening, I have so much to learn...

I have attached some pics. Note, healthy one is showing slight twist which was fine yesterday. Also purple stems on both which I'm guessing is due to temps rather than nutrients?
Sorry about photo colour - the lights are on!