Hello, I am on my first grow and have been in the flowering stage with my plants for the past 4 weeks. One is a hybrid sativa called larry kush and the other is a hybrid indica called jamaician kush. I'm using a 150 watt High Pressure Sodium lamp 12/12 cycle with two desk fans blowing in the grow closet. I purchased the plants as clones and vegged for 3 weeks 24 hrs light on and then switched to the 12/12. I originally transplanted the clones into 5 gallon pots using fox farm ocean forest. I did not feed them any nutes, only water from my reverse osmosis faucet. For the past few weeks the plant size growth has slowed considerably and the majority of growth appeared to be in the buds. About this time I also started noticing the ends of the leaves getting yellow and sometimes the whole fan leaves, along with some leaves curling upwards and getting crispy dry on the ends. I have been watering about 2 cups every 3 days or so when the upper layer of the soil is dry at about 1.5 inch. My sativa has grown taller than the indica and the very top has been about 6 inches from the bulb (I have a fan blowing between the top of plant and light, and when I hold my hand above the plant it does not feel too hot). I initially thought the leaves may be getting too hot, but some of the problem leaves(with dryed up and curled tips) where largely shaded at the bottom of the plant. Also, the bud at the very top looks the best and it's fan leaves are not dryed and curled. I then figured that it may be a nutrient deficiency, so I puchased fox farm big bloom and cal-mag. I mixed about 1/3 recommended doses of each with water from the reverse osmosis faucet and fed 3 cups of the mixture to each of the plants. I have thus waited 4 days since doing this and the plants do not appear to be improving. The next thing I am going to try is moving the plants away from the 150 watt bulb and go back to feeding them just water. Also the temperature in the grow space ranges from 65 at night to 85 in the day. The humidity varies between 25 and 55 percent and I have not yet monitored the pH of either the water, nute water, or soil. I have attached some photos to help with a diagnosis. Any help is appreciated.