A little closer for the 1300 PPFD. Between 31-32 inches at 100% for the 1300 PPFD. 34/35 inches for the 1000. Since I got 2 in this 4x8 I run them at around 30 inches at less power to save some power and help the boards last longer instead of raise them. Depends on the coverage your after, the layout and reflectiveness of the surroundings, and light lap also of course.