Thank you so much. I I was hoping to find somebody who was using them. Your answer gives me a lot more confidence to keep them about the same as my HPS. I'm probably 24 to 26 in a way and my temperature stays around 75 to 77 degrees. Thank you for your help it is very appreciated.So I don't have the 630 hood, but I do have 2 315's going. In my experience, you can keep them closer than the HPS because there isn't as much radiant heat. That being said, it still gets hot. I kept mine maybe a couple inches closer than the HPS. The top of the tent is too high. You won't get the penetration that you did if you were running a 1000w, so start it low and move it up as needed. I absolutely love the lights, and so do the plants. You will not regret the switch.