other systems such as gravity operated flow systems pressures in the assembly 10 are not as high in this instance valve 58 would be shut as valve 54 is opened by sensor 56 in these systems when this occurs the entire system would experience a drop in pressure and a corresponding increase in pressure when valve 54 is closed and valve 58 is opened such pressure fluctuations are beneficial due to ozone diffusing more rapidly into the water when the pressure is higher as a result more ozone diffuses into the water sooner to develop initial higher concentrations of dissolved ozone still referring to fig1 another feature of applicant 39 s invention may include premixing ozone gas with another sanitizing compound prior to insertion of the mixed compounds into the flow of water here a venturi injector 62 similar to a venturi injector as shown and described in applicant 39 s pending application ser no 09 393 437 and which is incorporated herein in its entirety by reference this venturi 62 is conventionally provided with a water inlet 63 and a water outlet 65 through which a motive flow of water as indicated by arrows is pumped by a water pump not shown venturi 62 is also provided with an annular cavity 65 diagrammatically illustrated in fig1 which in turn communicates with at least two sanitizer injection ports 64 and 66 as shown port 64 may be coupled to a canister 68 having a removable.