Red Sea No3 test

[Hella_Reef]

Just curious to see if I'm missing something rite in front of my face with this test. I have been testing and getting .25ppm for No3, and was wondering how do I get low range readings. I want my tank to be at .2-5ppm for sps, Is this only feasible with salifert test kits to read lower nutrients? Or is their an equation involved with the R.S. kit as well? Thanks

 

[Wingizzmo]

Use red sea pro test kit