I use the 4ft 8 bulb T5 for a grow. With 5 Hashberry under them, I hardly have enough light. I had to add 2 single 4' T5's for the sides and that didn't quite cut it either. Like StinkyAttic recommends, I have a very thick canopy and have to turn the plants daily to ensure adequate light coverage. They are 4 weeks into flower but boy is it a struggle with the T5's. Now for veg, they were awesome. Make sure you use the 6500's for veg and 3000 mixed with 6500 for flower. I am using 6 3000 and 4 6500 for flower. This is my first T5 grow. I will keep everyone posted.