plant color and height???

as far as i know magnesium will darken the leaves of the plant but these leaves inordinately dark. i dont currently have pictures but from experience could you give me advice as to how to lighten the color or if i should jus leave it alone. also, i turned my lights off the other night. why? i donno impulse i guess. but it seems to not be growing very much after that. any ideas??? what i could do? what i caused? anything? (plant is bout 1 1/2 ft. tall and aprx. 8 weeks old)
thanks

it could bebecause its a short indica, maybe its genetics, may not.

what i would reccomend is to flush every2 days for like a week or 2 and then feed regurlarly with nutes, sounds like you got something wrong with the growing medium

would adding ash from my fireplace help the color? could the color be because the soil is very acidic?