I have this tank in my bedroom and I have the saame exact "problem", which in my opinion is a plus for the tank! Fist off it isn't just the light but the motor for the filter, it gets really hot too. Make sur eyou have enough water to cover the outside of the motor. Both work as a heater for me in the summer.
I would not put the light on during the way, I would wait til the sun starts to set to turn it on unless your house stays in the 70s with central air. All summer long I do not use the heater unless it is dropping to the 60s at night, then I turn the heater on or just leave the light on. I think this is a great tank partly because of the light and filter creating so much heat=less energy the heater eats up
edit: As for Algae just use this stuff. Algae eaters will do you more harm then good in that tank(you would have to get a snail because of the size and their bio waste will cloud the tank up too fast >_<