Abstract: A smart pool maintenance monitor and alert system configured to communicate with an internet-connected device is described. The system employs a floating buoy for use within the water of a swimming pool or hot tub, and a gateway. The buoy is equipped with a variety of environmental sensors configured to accurately and expediently measure water temperature, pH, salinity, water level, air temperature, UV index, the ORP index of the water, and other environmental data. The data is conveyed via a wireless radio to the gateway, which interprets the data, stores the data in cloud storage, and relays it to a user's mobile device where it will be displayed by the applications downloaded to the respective user devices (smartphones, tablets, laptops and PCs, as well TV Set Top Boxes and wearable devices). The gateway is configured to convey alerts to the user when measurements are not consistent with those of a safe and hygienic pool.