General Hydroponics pH Test Indicator makes testing samples easy. Simply fill a test-tube halfway with nutrient, add a few drops of pH Test Indicator, and observe the coloration of the liquid in the test vial.
Many experienced growers prefer this pH Test Kit to expensive electronic meters because of its reliability and ease of use. Super concentrated, just a few drops per test. Measures from 4.0 to 8.5.
Replacement solution (8 oz.) is available.
To optimize plant growth indoors, the pH level of your nutrient solution should be between 5.5 and 6.5. Adjust with pH buffer solutions, as needed.