well first u will have to buy a new light if u wanna upgrade u can buy a higher watt bulb and use it.2nd they dont make a higher watt pc to fit that. and 3 its only 2.8 watts per gallon i would think of something else. and look online, its more than likely cheaper online with shipping than buyin from lfs. and 4th a 90 gal is a deep tank so i would consider a canopy that u can retro fit power compacts or vhos u can fit more than 4 pc in there. or metal hal. lighting. i have the kinda the same light on my 55, well 240watts pc and your tank is almost double, so if you only want to keep softy and lps go with power compacts or vho's. u can keep corals with that light, but u cant upgrade it later so i would just upgrade now and save urself money in the long run!