Hello,
I have a 29 gallon and have Live Rock and Live Sand and my nitrites, Nitrates and Ammonia are perfect. I believe in the live because I have a small animal living in the live sand making small holes and eating the left over waste and food.
I think you need more live rock and live sand, add a protein skimmer and a good filter with 2 or 3 good powerheads to move the water around in the tank.
Thanks,
Greg