help ?

was just wondering i have 3 plants i have 4 f40 bulbs going and a fan on them all. the temp is from 75-80 and the humd. is usually35-40 i keep the light on 24 hrs. two plants are turning a neon yellow with a hint of green but still look strong the other is dark green but droopy i water when the soil cracks i feed every other watering with m.g. 1/4 teaspoon i no the soil i bought was from wal-mart and had food in it? am i over doin it and they are turning yellow and the dark one is it supposed to droop like that?????
any help would be much appreciated
thank you
i am adding pics
or am i just overreacting?
first grow and am really enjoying maybe i am fussing over them to much? any info would be appreciated when do you think i should 12-12 them to force them to flower
thank you
again

ok the one that is getting pale, this means the plant is hungry and needs more food,

that dark one is good on food cuz its not getting pale, but its drooping because its overwatered

Overwatered = drooping

Hungry= pale yellowish green