Hmmmmmmm if you have unreadable Ammonia and readable nitrites that wont quit along with a radable nitrate level, I suspect tha accuracy of your test kits.
Running a UV sterilizer in its self shouldn,t cause nitrates to drop, though if you have a large bacteria population being killed off by the UV its possible to see a
nitrite spike.
My experience has been that most hobby level kits are lacking in precision and at best adequate for charting trends. I recommend taking a water sample to a local fish store or two and see what results they come up with
Be skeptical
