I would definitely check the wattage on that light to be sure you are not keeping it too close to your plants...but as for "browning of the leaves", I don't see that in the pics you have up. The third one shows a very nice green and healthy looking plant, and the second is obviously under hps lighting that distorts the true coloring of the plants. Find out the actual wattage of your light, and follow the advice in the lighting section of the forum as to proper placement so as to keep your babies safe from burning.