Each zone of your spa will have an air venturi control. This regulates the amount of air that flows through the jet with the water. The more air, the more powerful the jet’s stream.
You can adjust the pressure in the entire seat by adjusting this air venturi control clockwise or anti-clockwise.
Upon completion of spa use the air venturi controls should be turned back to the OFF position (no air through jets). This prevents air entering the spa and cooling the water when spa not in use.