General Hydroponics pH Control Kit Designed to work superbly in hydroponic environments, both soil-less mixtures and soil grown plants Includes pH Test Indicator tube:fill a test-tube halfway with nutrient, add a few drops of pH Test Indicator, and observe the coloration of the liquid in the vial. Includes 8oz bottle of pH Up which is used to elevate it to the desired level Contains 8oz bottle of pH down which uses food grade phosphoric acid to lower the pH to to the desired level For best results, discard and replace hydroponic solution regularly