Bestva 1500 hanging height got new light not sure the distance from plants to light any help would be great right now its at about 22in from ground I'm not sure if I measure from the plant 24 in or 24 from the ground same goes for flower have no lux metter yet
I would say the distance from the top of the plant to the light. Start with 3 feet, then move the light down by a few inches and see if you are getting any burning or wilting. I wouldn't go any closer than 18 inches.
You might want to add a fan to lightly blow across.
I would add some reflective material to the boxes to get better lighting from all sides.
Good luck