Ok, you do have high light, so any phosphate in the tap water will not stay in the tank very long before the plants use it. The same is true of nitrates. And, it doesn't matter what brand test kit you use, if you are going to make a critical decision about fertilizing from the test results you have to calibrate it first. I have to suggest that you do the regular EI fertilizing routine.

How do you measure your CO2?