[Snaz]

Nitrates over 20ppm is cause for concern so yes you should address that soonest.

How many pounds of Live Rock do you have? Nitrate sources can include:

Dirty filter media such as floss, sponges. Make sure any media is replaced or rinsed as soon as it gets dirty, has ANY smell or just looks dirty.
Try testing your new water before adding it to the tank, might be bad water or salt.
Substrate - Are you using crushed coral? Lots of people complain CC is a detrius trap and causes their tests to climb up, especially if your a heavy feeder.
Left Over food - When you feed is everything eaten within 15 mins? Any food go uneaten? I rinse all frozen food before I place in the tank.

You night also want to try a handful of chaeto in a floating soap dish or just balled up and sitting in a corner. Chaeto is a great nutrient export. Maybe your test kit is faulty. Take a water sample to a buddy or LFS and confirm the results.