The GroLine HI98118 pH/temperature tester is our latest pocket meter for measuring the pH of a hydroponic nutrient solution. This modern looking meter is only 0.7" thick and extremely ergonomic, fitting comfortably in your hand. The HI98118 has a very large easy to read LCD display that shows both pH and temperature along with calibration, stability and low battery indicators. All operations are simplified to two buttons. One is for turning the meter on/off and the other for automatic one or two point calibration. Two-Button Operation Quick Calibration Mode using Hanna Quick Cal pH/EC Calibration Solution Cloth junction providing a larger surface area than a standard ceramic junction GroLine Waterproof Hydroponic pH Tester The HI98118 GroLine pocket pH Tester is an affordable way to measure the pH of hydroponic nutrient solutions. The maintaining of an optimal pH is essential to maximize optimum growth. The general rule of thumb is that as pH increases the solubility of minerals and nutrients decrease. It is important that nutrients are soluble for plants to uptake and use for growth. The pH of nutrient solution can also affect the bacteria that fix nitrogen for the plant to use. Every plant has optimum pH levels for growth. Below is a table for the ideal pH range for a variety of plants. The HI98118 can be used to measure the pH in soils as well as nutrient solutions. The North Carolina State University has outlined a procedure known as Pour Through Sampling Method. This method is used for container plants in which 50 ml of leachate is collected from a thoroughly watered plant and then tested. To measure the pH of soil as a slurry the USDA recommends a mixture of 1 part soil to 1 part water. The slurry is allowed to rest for 10 minutes so that the solids will settle out and the pH of liquid above can be measured.