yellow leaves brown spots help

so I have 2 plants, one is good the other one is dieing (i think).

A week ago the leaves started curling (from miracle grow) so i have been giving it water all week to stop the leaves and get it back to normal. but now the leaves have gone yellow with brown spots on them.

pc grow box
3 CFL's 15 watt
northern lights female auto flowering
ph: N/A

Have you flushed the plants and allowed the soil to dry out at all? When you say you've been giving them water all week, it sounds like over watering, in a week you should water maybe twice, 3 times max depending on humidity.