wpg is an old school of thought for lighting. Wattage is really a rough measure of water penetration. it is really about Lumens and PAR, but for without getting into that, it's really about the type of lighting. PC's are bare minimum for softies and LPS. monti is the least light demanding SPS and possibly could survive under PCs. i would place it very high in the tank, and make sure you have good flow. flow is almost more important than the light. if you are getting detritus collecting on it, you dont have enough flow.