The Viagrow pH down liquid nutrient adjusting solution is formulated using the highest food grade quality phosphoric acid and is safe for all food crops. The Viagrow pH down is highly concentrated so less is needed for use as compared to most brands. Viagrow pH down can be used in all growing mediums - Soil, soilless, hydroponics, or to adjust a foliar application. Maintaining a proper pH is an important part of growing healthy plants. To grow the most vigorous plants maintain a slightly acidic pH in your choice of growing media. It is recommended that the pH for most crops fall between 5.5 and 6.5. Use moderately. Add 1 drop at a time to the plant nutrient solution and then test the pH. Repeat application and test again until appropriate pH level is achieved.