Yellowing leaves, and curling

I just wondered if someone could help me with this. It's a 4-week old Aurora Indica and although it doesn't seem to be dying, it does seem to be growing very slowly and the edges of the leaves are starting to go yellow and curling downwards and I don't know why.

It's growing under a 200w fluorescent light which is 12" away. In the pictures there is some harsh burning on the lower leaves and I think that was caused by heat damage being too close to the light so I moved the light 12" away and the burn hasn't got any larger, but now the new leaves are going yellow. I water it every four days.

Any ideas?

E-indoor or outdoor: INDOOR
E-soil, soilless, coco, aero, or hydroponic: SOIL
E-specific medium: GENERIC SEEDLING PEAT/COMPOST
E-Water source: TAP WATER
E-Source water pH: UNKNOWN
E-Age of plant: 4 WEEKS
E-Type of fertilizer: NONE
E-Rate of application (if hydro, this is your PPM number, preferably after each component is added): NONE
E-Lighting source and distance from plant: 200w CFL, 12" AWAY
E-Air temperature (both day and night if you are running a dark period): UNKNOWN
E-Air % Relative humidity: UNKNOWN
E-Lighting schedule: 24 HOURS
E-Type of ventilation your room has: IT'S IN A CUPBOARD, I LEAVE THE DOOR OPEN MOST OF THE TIME
TR-Did you pre-soak your media in pH corrected solution?: NO