Algae in tank?

[freeflow246]

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.

[Oldfishlady]

It is normal and expected to have some algae in a container of water that has both light and nutrients.....some species of algae is a sign of a healthy system, however, since this is a closed system-it needs to be controlled by manual removal along with the regular water changes-some algae can help make the tank look more natural and soften edges-it also provides a place for microorganisms that are healthy for the tank/system.

The sunlight-can cause algae to thrive better-so if you can either cover that area with dark background or move the tank itself so that it receives less direct sunlight that will help some.....along with manual removal and vacuum......depending on age of lights, nutrient load and photoperiod you can limit some of the algae growth

On the 2.5gal-do you have a filter, live plants, type of additives, water change schedule, any tank mates, age of setup, type of lights, age of bulb, how long are the lights on.....you can control some of the algae but you should always have some......

Can you post a pic.....

[freeflow246]

No filter; it died after a day or two. *sigh* The only live plant I have is a moss ball, and it has been in the tank for longer than the heater without causing any sort of algae growth. I had slime coat in the water to heal Jalen's fins and to make the water safe, but this time I'm going to try normal water conditioner to see if it makes any difference. I change the water twice a week; 50% on Wednesdays and 100% on Sundays. No tank mates. I've had the setup I have now (fish, decorations, moss ball, heater) for a week. I don't turn the light on unless it's night and I need to check on something. The light is very bright, and makes the lid hot. But the tank is right in front of a window, and gets natural light from about 7:00 AM to 8:00 PM.
I already cleaned the glass, but here are some of the decorations. There's more on the log, but there are one or two spots on the fake plant.

[Oldfishlady]

Looks like green spot and diatoms....both normal and expected-the diatoms are generally caused- due to new system and can also be caused by old light bulbs or poor lighting-but with natural light-it is most likely caused by new tank....both need to be manually removed with your regular water changes-an algae scrubber should take the green spot off and the diatom should wipe off pretty easy with your hand and then vacuumed out or remove with the 100% that you are doing......not a lot can be done that you are not already doing since the algae is normal and expected with a container of water that has both nutrients and light.......just part of the general care in keeping a tank/fish........

[freeflow246]

Alright, thanks for your help! At least I know it's nothing to worry about. :)