leaves curling help plz

ok im a first timer. the leaves on my plants are curling they are only 4weeks old. i have noticed that it curls more about 2hrs before the light is put off but i looks worse in the morning n slowly looks better till night rolls round.
now i dont have a camera but i found a pic on the net that looks exactly like mine but the setup is different so i need help its the first pic on link

leaves curling up....

the leaves arnt browning though just curling my setup is this:
250watt light 2ft above plants
day temp 25-27...night temp 22-25degC
grow space is 120cmX120cmX200cm
they are in a premixed soil with good drainage
soil ph is 6.6 n water is same
light cycle is 18/6
i only gave them a starter fertilizer that boosts there disease resistance n that was when they first popped out the soil. i thought at first that it was heat so i put a fan in and raise the light but it still the same if not slowly getting worse

any help would be great thanks cos im getting sooooo stressed out :pimp:

How is ventilation? If you have a fan blowing on the plants 24/7 they will curl up like that. Also, if room temp at night is 22C or 71F as im use to with that scale, a fan blowing on them at night will make it seem cooler, which is too cool for them. As the day goes on they warm up. I could be wrong though. Also, when a plant is curling, it is either trying to retain water, or sweat it out. Curling up I think is sweating it out.

You shouldn't feed them anything until they have a good root structure and then only lightly. Since they are starting in soil, the soil should have enough nutrients to grow them for 2-3 weeks (from seed). Then transplant into the container you will use while they flower and they should grow well. Do the same when you transplant them to a larger container, wait a couple weeks before hitting them with nutrients. Bat guano is good because it is hard to burn them. Never give more than it says on the label. Good luck. :thumbsup: