All hot tubs have Venturi valves. This allows air to mix with the water before it is shot through the jets. When the air sensor pad is activated, the air blower forces air through the injectors, creating a turbulent bubbling action. These bubbles give a gentle massage and can even have aromatherapy added to them to enhance the experience! Air injectors may cool your water a little bit. These injectors are located in the seats and footwells and strategically placed in your hot tub to give you an extra added massage apart from the jet experience.