Should there be stuff growing on my filter?

[Anathema]

My 2.5-gallon aquarium has had this problem for almost a year now, and I'm starting to really find it annoying. On the part of the filter where the water exits out of to go back into the tank, I have like, a plant/algae thing that just won't go away. It's bright green on the filter, and is also sprouting leaves on the filter pad. I dunno what it is, I've had the problem before I put a live plant in the tank, which I thought might solve the problem, but the plant hasn't helped at all. Before the plant, I tried some algae tablet, which got rid of algae on the front of the tank, but didn't affect the filter. It's just been annoying me, every time I clean it off, within a week, it's back again. The tank is in the living room, which has a big back door with blinds that are open most of the day, so maybe the sunlight is causing it? I'd move the tank to a shadier area, but there's no room for it anywhere else.

Maybe I'm doing something wrong? If anyone could help I'd appreciate it.

 

[WILDER]

I'm afraid with only a 2.5gal you will have a lot of problems, small tanks are hard to maintain, what fish are in the tank.

 

[Anathema]

Just a male betta.

 

[WILDER]

You want to post this in the betta section you will get a bigger response.

 

[playfulalliecat]

I may be wrong but I think its just algae that is growing and feeding on the bacteria and stuff in the filter. I don't think anything is wrong. All of my filters do this. As long as it's not all over the tank, I wouldn't think it should present a problem.