As a rule of thumb,
the Z140 came ozone
ready but without
one. So you had to
add the ozonator.
But to confirm, the
Z140 has a socket
either on the side
or bottom of the
control box labeled
OZONE. The socket
will be next to the
pump plugs and light
plug. IF the socket
is empty, you don't
have an ozonator.
FYI: if the spa
never had an
ozonator, it IS
ozone ready. You
will need to order
an ozonator WITH a
mazzai. Install is
pretty easy.