I've been going crazy the last couple of weeks, my API nitrate test kit has continuously provided readings from ~60 to ~100 for the tank. I've tested my RO water and the water for the water changes prior to adding them and they always read zero. When I test the effluent from the denitrator it also reads zero.
I'm thinking the API test kit only reads zero accurately. The plan is to hit the LFS this afternoon to see if they have a Salifert nitrate kit to confirm my guess.