Well a couple things for you buddy...first of all you need to get your plants on a more consistant light scedule I would recomend a 18/6"18 on 6 off":thumbsup: at first this keep your nodes close and tight and also give the max amount of light while still allowing for a dark period..wich is important for cellular growth,also the yellowing on the bottoms leaves is a dead give away to nitrogen deficiancy so bump up your pertilizer but dont over do it give them some high nitrogen fert like say a 16-8-6 or something close your problem will work its self out with in a week hope the info helped my friend....