How do you know you lost a lot of PAR? The quantum Meters (mostly Apogee) that are available to most of us are incapable of accurately measuring PAR at these wavelengths. While the water will quickly filter out UV light, much will reach in to the tank a foot or more (depending on power level, of course). IME the more colors you use in your setup, the better the colors will look, just be careful how much you use. It is easy to use too much red and green.