I have a 150 gal. From my light which is a fluval plant to the bottom of the tank is 27 inches .It is set at 78% on all the spectrums except blue which is set at 20% I grow val, anubias, crypts ,swords, staurogyne repens, susswasetang,xmas tree moss, bolbitis, aponogeton, I don't have success with most carpet plants or stem plants except a plant I call star grass This light seems to work for me ,after researching all the possibilities