Is closer to the light much better?

Growers using CO2 can bring their lights much closer without hurting the plants. Go find your light in an online store. In the description somewhere, there should be a ppfd map (usually 2 or 3 of them). They look like grids with numbers inside, the numbers being the ppfd at the given height. Without CO2 supplementation, you want: 400 ppfd in seedling 600 ppfd in veg 900 ppfd in flower Follow these guidelines and you won't end up burning ypur plants like a lot of people seem to do.