You should check out Sanjay's research on the LED fixtures. He made 24 inch and 36 inch square grids and measured the PAR levels from the bottom of the tank to the top. It looks like a topographical map with differing colors for the PAR levels and shows precisely how good the light is for all major LED systems. Depending on the animals you want to keep, I am sure this would be helpful to you. Here's the link: Manhattan Reefs - Sanjay's Lighting Guide