So I've decided to use HPS from start to finish. Will probably add a few CFLs for the veg. But...how far away should the seedlings be from the light. They just sprouted today. I know the final distance will be 30cm but when should I do that? right now I have a 1 meter distance. Thanks in advance
Like 1.5 feet. Put your hand under, is it hot? If hot too close. And, I believe just using the HPS is the right way to go. It's what I do. There's just no need for anything else. I've had subpar results with LEDs and the Metal Halide doesn't do any better than the HPS--results were exactly the same whether I changed up or not.
I keep my HPS mounted 8 feet up at all times, and yes I veg under them too. I don't bother moving them up or down. Keep things simple and easy on myself , life's difficult enough as is. The T5 in my mom/clone/pheno tent also stays at 7 foot ceiling.
Only HPS Id use is the Hortilux HPS Superbulb. They make it 400-600-1000w. 1000w Hortilux is 1600umol I have used a 1000w Hortilux HPS for 20+ years for Seedlings-Flowering. Seedlings get around 24 inches. They can be done closer, but as was stated earlier, put your hand under it for a bit of time, and see how hot it gets. I also use a thermometer. I like between 76f-83f, with a constant breeze. Lights on, and off. Always a lot of air movement. I veg 24 hours a day. I always use 1000w Hortilux for seedlings, but am experimenting with Gavita 1700e/1700umol-645w with stellar results. Am a die hard HID guy, but I think Ive been converted. The Gavita has insane umol readings, but is expensive. The Fluence looks killer too.