Hanna GroLine Waterproof pH Meter

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.

The HI98118 is an advanced meter while maintaining simplicity. The front of the meter has two buttons. One is for turning the meter on and off while the other is used to enter the calibration mode. There is a third button in the battery compartment that allows the user to customize the meter to their preference. Customization includes temperature readout in oC or oF, automatic shut off selectable from 8 minutes, 60 minutes or disabled, and lastly the choice of using Hanna’s Quick Cal pH/EC standard or traditional buffers values of pH 4.01, 7.01 and 10.01.

The HI98118 features a unique extractable cloth junction. The reference junction of a pH electrode, also known as a salt bridge, provides an electrical pathway between the internal reference cell and the sample. Any clogging of the junction will result in a disruption of the electrical pathway. When this happens the readings will be erratic and take a very long time to stabilize. With the Hanna extractable junction a small portion of 1/8″ is extracted or pulled to expose a clean surface. With the junction renewed the clogging is cleared allowing the meter to still be used. The overall length of the junction is about 1″ so the junction should only be extracted periodically.

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.

Features at-a-glance:

• Built-in temperature sensor for Automatic Temperature Compensated measurements.
• Renewable junction to clear any clogging that causes readings to drift and be erratic.
• Stability indicator that disappears once a stable reading is obtained.
• Automatic calibration to one or two points at a push of a button.
• Uses Hanna’s Quick Cal pH/EC standard with a pH value of 6.86. The standard can also be used to calibrate conductivity meters to 5,000 μS/cm.
• Battery % level remaining displayed at startup.
• Low battery indicator that is displayed when less than 10% battery life is remaining.