hello, we are new to this site, hope we can learn more than we already know. so, we have had our 72 gallon bowfront for 4 years now and a 32 gallon corner for 2. most of our original fish are still in the 72 gal. (2 lepuranus, 2 bala, 1 clown loach, 1 pink tailed something, 2 chinese algae eaters). anyway we always seem to have green scum on the bottom of our glass lid. is it because our water level is too high and the hot lamps are doing it? I was thinking of getting a new light, like those that stand above the tank,http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=12772. also how do you really know how much light wattage you need? and will the lunar lighting be beneficial to our fish if we get that light?