It covers a wide range, ranging from 4.0 to 8.5. Just half-fill the tube with nutrient solution, add 2-3 drops of the pH tester, shake and see the resulting color. Compare with the color scheme of the vial to check the pH level. Very reliable and easy to use. Suitable for 1000 tests. Instructions: Pour the solution to be measured into the supplied tube. Add a few drops of the indicator solution and shake. Read the pH according to the color on the scale.
