nitrate

Hi all, I am currently 4 weeks into trying to fish-in cycle my brackish Fluval Flex 15g and I still have NO NitrItes or NitrAtes! Tank conditions bellow: pH: 8.0 SG: 1.010 Temp: 27c/80f Ammonia 0.50 ppm Nitrite: 0.00 ppm Nitrate: 0 ppm Heres the story. I went to my LFS and told them I was...