Is my marijuana sick?

A question from a fellow grower:

i have a few plants and i fear they are sick or lacking something but for the life of me i cannot figure out what or how to rectify the situation. my plants are a few weeks old i am using cfl lights a few inches away from the plant. the light/dark ratio varies a little bit cause i don’t have a timer. they often get 24h light. but i try to give them a few hours of darkness a day when time permits it. they are grown in potting soil. i feed them musky 5-1-1 fish emulation fertilizer once a week. i water them when they are dry. i check on them 4 times a day. the temparature ranges from 20 celsius to about 30 celsius. its really cold where i am so this is the best i can do for the moment.
my problem is that the leaves are changing colours they are light green around the edges. then turn yellow. i have attached pictures to further illustrate what i am trying to say. What can i do? Thank you for your time and your help.

ps: i have already transplanted them but it did not solve the problem. they were not root bound.