Are you sure that it is zero trates and higher trites? That seems backward.
How often do you do water changes? What filtration do you have? How often do you feed?
Nitrates build up and are removed by partial water changes. If you do not stay on top of those, you will see those levels creep up. If they don't come down, it is usually from overfeeding and/or filters not being cleaned regularly and/or detritus (poop) build-up in the tank...could also be overstocking.