I posted the same thing on your blog as the guys above have posted. I went to your blog to see what you have been doing to the tank, but there wasn't much explanation there. Anyway, as stated above, your ammonia and nitrite reading should be zero (0) at this point since the tank has been up for such a long time. Nitrate is hardly, if ever, at zero (0), especially if your tap water already has nitrate in it.
Since the nitrite level isn't at zero, and you are experiencing some ammonia issues, the only thing I can think of is that you are disturbing the bacteria colony too often. What are you using for bacteria to grow on? The beneficial bacteria can grow on glass, plants, fixtures, and filter media (e.g., Bio-balls, Bio-max).
First and foremost, I would recommend that you do some reading on the nitrogen cycle in a tank, and that you figure out what beneficial bacteria are, how they grow, and what cycling a tank means. After that, you might have a better grasp on how to address your problem.