The water jets provide a hydrotherapy pressure jet. It is a closed circuit, where the water is absorbed by 1 or 2 pumps (depending on the SPA model) through the drain and driven to the jets.
The hydromassage effect is provided by the jet, when the circuit water mixes with the outside air, in the so-called Venturi effect.
To adjust the amount of air driven into the jets, simply turn the air input tab (venturis) as follows.
Each air inlet activates a certain group of jets.
Some jets can also adjust the flow intensity on opening and closing the water flow. To do this, proceed as follows: