my 2 month olds are showing some yellow tips. hear are some specs. 5 gallon pots. soil is half schultz moisture control, quarter earth worm castings, and quarter vermiculite. the have been feed once with mg all purpose fert at half strength, they drink about every 4 or 5 days. both are supposidly northern lights. 2x250watt mh, sylvainia lamps under a 3'x4' reflector. sorry no pics i'm using a ps3, but i will be as descriptave as posible. they have no curling, drooping, and the tips are only yellow less than a quarter of an inch from the tips on older fan leaves, new leaves look great, acctually they look great in general, just noticed tips yesterday. i would like to fix the prob b4 it is a prob! lights are 14'' away, temp is to cool (68 69 during the day) 18/6 lights. one was topped 2 weeks ago and clone is doing well. the fist feeding was 4 days ago.