Thermometers used in the pools and spas measure the temperature and the humidity in the pools and spas. If these values are not measured, the mechanical equipment used in the pool or spa will get damage. Because of this, the temperature and humidity must be kept in optimum levels in pools and spas. We have to use pool and spa thermometers for this measurement. Poolline pool and spa thermometers have many models –from the economic ones to the joyful and funny ones.