Check soil pH at multiple depths wtih the Control Wizard Accurate pH 8. A professional Soil pH and Moisture Meter with 12-inch probe for extra large planters, the Accurate pH 8 utilizes the electronic ground field effect of the earth on two dissimilar metals. This meter can measure pH and moisture at depths up to 12 inches. No batteries are required. This meter comes with a cleaning pad and 6 month limited warranty.