Abstract: Fittings for the recirculation system of a pool in which a Venturi T-fitting has an air inlet connector. Water entering the inlet end of the T-fitting advances through an adapter, which is in threaded engagement with a Venturi insert formed with a discharge orifice. The insert is formed with a nut-like projection. The water entering the adapter is discharged through the discharge orifice of the Venturi insert as it is mixed with air under pressure so as to be aerated. The aerated water is discharged from the Venturi T-fitting for passage through an inlet fitting for the recirculation of water in a pool. For regulating the size of the discharge orifice, the Venturi insert is removably replaced.