Been wondering how my tank was always 0ppm for Nitrate reading. Today I figured I wasn’t shaking the test tube enough. It actually makes heaps of difference shaking it for 1min instead of 5 sec. As you shake it, the colour actually changes on you (assuming there is a Nitrate reading)!
Just thought I’d mention that to anyone who was wondering why they have perfect Nitrate readings all the time. Try shaking the test tube more.
I’m using a Master Test kit from Aquarium Pharmaceuticals (API).