I recently added a heater to my 2.5 gal, as the weather down here will be cooling off soon, and I wanted to make sure that the heater would work well before winter started rolling in. The heater works fine; keeps the temp around 80-84, which Jalen loves (he built a nest the day after I turned it on). Today I went to do my first 100% water change since I installed the heater, and I found green algae growing in one corner and little green and brown spots on the back of Jalen's decorations, the side facing the window. I hadn't noticed them until now.
I'm not too worried, as Jalen seems fine and the algae is coming off easily, but is there any way to prevent algae from growing? I'm assuming the algae started appearing because my tank is warm, but the heater will be necessary in a few months. Also, my tank is by a window, so there's no easy way to keep it from getting sunlight. Any advice?
EDIT: Also, my water stinks. It never has before.