Originally Posted by Byron
My API nitrite test kit is an old one [don't use it any more] but the instructions said to leave the regent in the tube for 5 minutes before comparing the colour. That may have changed...
+one, There is a right way and a wrong way to perform the test's.
Leaving solution set too long,not leaving solution set long enough,not begginning with enough water for sample, or too much water, can all result in inaccurate readings,confusion.
Best to follow directions exactly as written.