I use 650w LED, tbh I stay bout 20-24 all the time with this light and the plant seems to love it. As a youngin I had to keep it slightly higher because my new growths was sun burnt.
I've actually had it 6inch for the 1st 18hours of light, is this a major issue i should be worried about? my light is due back on in 2hours am looking forward to moving it away from my poor baby's !.. thanks for the reply's