My nano tank is completely stock I have the 28gal quad. What should I change in the filter/media tray that came with it? I read alot about the chemi pure elite. Is that something you can use over and over every month? I have been having a green algae problem and now Im seeing some red slime. Im hoping the chemi pure will help out with that. Im not sure how to use the chemi pure either. Do I just need to buy the small bags for it and dump it in then install it in the tray? What about the black sponge looking filter? Does that get changed out?