some MH and HPS bulbs give out more than 50k lumens. since you've had them since september, i say blast those babies with however many lumens you can! during the veg cycle you have to make sure to use a blue spectrum light. do you know what temperature rating the bulbs run at? 5000k-8000k are best, followed by the 4000-6000k temp ones (covers the blue spectrum/veg, red/flowering comes later). make sure to check soil ph, water ph, properly feed and water them and you should be good. your plant could be destined to be short, though. i've heard of lowryder plants that are supposed to yield great but stay short (always think positive) try to get some pics!