I have a 400 watt hps and a hydro system. I was wondering for vegging how far away should the light be from my baby's. It's only 4 plants if that makes a difference. Feedback would be great thanks.
I can safely keep my 400W HPS within 8-12" of the canopy. To figure out your ideal height you need to lower the light until you show signs of heat stress. This will require constant checking for about a day to make sure you have it correct.