So when in nature the plants grow in the heat of the days of summer the main growth is during the brightest parts of the hottest days. Days can be cooler of course but lets not digress. So that is the veg cycle time frame for the plants. When the light becomes less the plant starts to bloom. Less light. So I use in veg H/O blue spectrum t5s with 8 lamps, they are 48". The plants love it and I mean love it. You would be hard pressed to grow them faster or better. May I add here it is all hydro. My question is then with the great results under These why would they not do just as well under them with the red bulbs in for 12/12 blooming as opposed to a high pressure sodium lamp? I have that too in a 1000 agro sun but I am thinking if they grow so well under the t5s in veg that they would do at least as well under the t5s in bloom? Why would they not? Remember the blue bulbs would then be changed to red spectrum bulbs. Good question. Also I have two units that would be just a bit less watts than the one hps and have more surface area and, imo, a larger area of coverage. The heat issues would be less to a degree as well. Also my hps in on a 6' rail mover. Any thoughts that have real world experiance are welcome. Any good reasons in other words if you wish to respond... Thanks.....