Many growers stick with t5 lighting or metal halide lighting in veg. I had done this to for many years mostly with t5s and incandescent lighting up to a year ago when I had an extra 400 watt sunburst hood with an old metal halide bulb soon needing replacement. I replaced it with a red hps bulb and began to see much better results for almost all my strains. Metal halides, even 1000 watt, will produce more node space and a lengthy plant which most people see as good vegetative growth. While the plant is tall and very sturdy the amount of new node production is significantly slower and in most cases you will have far less nodes than you would under a red/yellow hps bulb. On the canopy under a 1000 watt metal halide alone you're PAR meter should read a healthy 400 at the proper distance. Now when you move the meter underneath the canopy you will lose a very large amount of light penetration dropping your readings to under 100, making the plant stretch more to reach the best light. Under a t5 light you have much better light penetration than a metal halide for what they cost to run. I would always recommend using t5s in veg before metal halide. When you test with a PAR meter under an hps bulb in this same way you will notice a far less significant loss of light penetration from 600 down to 350 and further away dropping to 100 so on.. ( The meter costs about 350.00 and is very useful but once you get comfortable with what your light will do you will rarely use it.) Sent from my LG-H810 using Tapatalk