I am not sure about the nitrite and nitrate readings... I didn't even know about those until I read this forum.
But I find that a smaller tank is harder to take care of. Even a difference from the 5 to 10 gallon. With the 5 I had a big problems with the lights creating too much heat and making problems that way. I even went to a lower wattage and it still was a big difference when I went to the 10 gallon, I liked it much better. That's why I am looking forward to the 25 gal... See how much that makes a difference.
Lea-Andra