Reliable and simple to use.
Fill the test-tube halfway with nutrient, add a few drops of pH Test Indicator and observe the resulting color. Red means the pH is too low, blue means the pH is too high (basic or alkaline), yellow to yellow-green is ideal. Many experienced growers prefer the General Hydroponics pH Test Kit over higher priced electronic meters.
1 oz test kit with test vial offers wide spectrum testing (pH 4.0 to 8.5). This concentrated solution requires only 5 drops per test.