DIY LED Light Questions

[Cal_stir]

my fixture is 1 inch above tank with no optics, the leds emit @ 120 degrees without optics, i find this to be perfect for my application, no spotlighting. i remember reading an article about a guy who used 40 degree optics and he had to mount his fixture about 12 inches above his tank to eliminate the spotlighting effect, my guess with 80s would be @ 4 inches.