General Hydroponics pH Control Kit accurately and efficiently measures the pH levels of your nutrient solutions, grow reservoirs, and the rest of your hydroponic system. pH control is essential for vigorous plant growth. Nutrient solution pH that is too high (basic), or too low (acidic), cannot be properly absorbed by plant roots. Incorrect nutrient solution pH can cause slow growth, sickly plants, and low yields. But General Hydroponics pH Control Kit is here to help. The kit contains everything you need to test pH levels and make adjustments so you can easily monitor and manage pH levels throughout your hydroponic grow. Kit includes: 8 oz. pH Up, 8 oz. pH Down, 1 oz. test indicator, a test tube, eyedropper, and pH Level Chart. To maximize plant growth, the pH level of your nutrients should be slightly acidic. Experienced growers consider the ideal pH for most crops to fall between 5.5 and 6.5.