I tested with API testkit, it's 0ppm. I find it hard to believe as i use saltmix with tapwater, but result may be true as I never put in any dead shrimp to kick start the nitrogen cycle. From my past experience, the aerobic bacteria will only work after 3mths, but my denitrator only run for 2mths only, and this slime has been around for a month already, initially my tank water is slightly milky due to this.
My tank size is 4x2x2.5 with a 5.5" YT, 2 maroon, 2 blackclown, all are healthy. Tank run only 2mths with Tunze skimmer, no sandbed. If this continue for another month, i think i will replace the deniballs.