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the pump. Check the suction by holding a small piece of paper (about 1" square) to the air inlet port of the
generator. There should be enough suction to hold the paper in place. Don't forget to remove the paper! The
amount of Ozone introduced into the spa can be controlled by adjusting the air control valve. The air control
valves should normally be closed on low speed operation of the spa and open on high speed.
3. WATER VENTURI SYSTEM for POOLS and SOME LARGE SPAS
A venturi draws air by forcing a set amount (or flow rate) of water through a pipe that gradually reduces in
size and at the smallest point in the pipe the venturi action (or air suction) is created. A venturi or venturi
system (see diagrams) must be selected to match the pump flow. Install the venturi on the discharge side of
the pump and after the filter. On large systems, the venturi may create an unacceptable pressure drop, if so, a
by-pass ball valve or spring loaded check valve can be installed. To increase the draw with a venturi system
that incorporates a ball valve, simply adjust, or slowly close the ball valve. This will create a back pressure
in the bottom pipe (see diagram) which will force water up to and through the venturi, thereby increasing
draw (or suction). A spring loaded by-pass check valve is suggested for two speed pump systems (usually
used on spas) to provide an automatic flow adjustment. The optional one inch venturi has a flow rating of 20
gpm and the 1
2
inch venturi is rated for 60 gpm with a 5 psi pressure drop. A ball valve by-pass is required
for flows over the rated flow of the venturi. A ball valve by-pass venturi system (see diagram) is
recommended for any pool installation, to offer a full range of adjustability.
