I suggest the first thing to do is keep up on water changes and use some kind of phosphate remover in your filter. If you don't have anything in your tank that requires light turn it off for a day or two. Your fish will be fine. But when you turn your lights back on don't turn them on for the regular amount of time. Start off with about 3hrs for the first few days then 4 and 5 and so on till you reach your regulare light schedual. If you just crank your lights back on the stuff will grow back just as quickly.