How Does It Work? SUStee Aquameter’s are a simple and effective way of monitoring the soil moisture of indoor plants to prevent overwatering and to also act as a reminder when it’s time to water. Simply insert a SUStee Aquameter into the soil of any indoor plant, water the soil, and leave the Aquameter in place. Over the course of several minutes, the Aquameter core will absorb and ‘wick’ the soil moisture up to the viewing indicator. As this happens, the indicator will turn blue. It will remain blue as long as the soil remains adequately moist for proper root growth. Once the soil dries the indicator on the SUStee Aquameter turns back to white, the roots are once again in need of moisture and the plant should be watered.