What type of medium; soil or hydro? SOIL What strain? GDP How old are the plants? 1.5 MONTHS What type of lights and how many watts? 600 HPS How far from the lights? 20 INCHES What is your watering frequency and source of water? 2/WEEK. 150 PPM TAP WATER. 6.7 PH What, how much and when was it fed? NPK? Every watering 1/4 teaspoon Jacks Classic Plant used to be beautiful. Then the top leaves went yellow. The yellowing has slowing continued down plant. New leaves are much more green than the yellow leaves though. The underside of yellow leaves are red?