i ran a 360W over the 6' 180g. 2 of them at 7" above the water would cover the entire tank.
loved the color and growth, works great with an apex or controller. definitely recommend over most other brands of LEDs to be honest. the spread and the light par is very good, and the way kessil overlays the lens' the light isn't as direct as competitor LEDs so the "burning" effect to corals won't happen.