General Hydroponics pH Control Kit
Contains Ph Up (add a little at a time when your nutrient pH is too low in order to raise the pH to the proper level), Ph Down (uses food grade Phosphoric acid to lower the pH to the proper level), and Ph Test Indicator (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. Use 3 drops per 5mL of solution).