Hanna Instruments Halo Direct Soil Bluetooth pH ElectrodeFC2022 Hanna Instruments Direct Soil HALO Bluetooth pH Electrode This Bluetooth enabled electrode turns your Apple or Android device into a full featured portable pH meter. Hanna Instruments Direct Soil HALO pH Electrode gives you the ability to measure, chart, record and share your data right from your phone. This direct soil pH electrode enables gardeners to go out and take pH readings directly without the need to conduct a soil slurry test. Simply