Recently installed a new spa pack and prozone ozonator. The unit lights and works. The problem is in the venturi suction from the ozonator. When the low speed on the heat pump is active the ozonator is on, but the flow thru the venturi is insufficient to draw in ozone. When the heat pump is on high, the suction is sufficient, but the ozonator shuts off.
The ozone circuit branches from the 1 1/2 inch pipe into a smaller 1 inch hose, into the venturi, then into the tub. I have inspected the venturi and it is not plugged, it would appear that not enough flow goes thru the branched pipe. I have gauged the suction with the ozone flex tube removed, and when on low flow the water comes out of the top of the venturi, when on high it sucks air very well and now flow comes out the top of the venturi opening.

Did the new spa pack include a new pump by chance?