I have a salt water test kit and when i test the phosphate the color card goes from real light yellow (0.0) to real drak blue (10.0). I dont know what color is a good color for the phosphate. I also can test the nitrates and the color cards go from yellow (0ppm) to real dark red (160) and i also dont know what color is a good color is for that too. it also tests calicum and i dont what good colors are, can anyone help?