22,
Each pool/spa can be different, so I would suggest you see what 3,000 RPM looks like.. That said, you should adjust the speed to what works for you.
As a test, I would ramp the pump up in speed and see of the pump fills with water or not..
Since you say it works in the pool mode, it would be nice to know the pool mode pump speed.
Another test you could do would be to put the system into the Spa mode and then use the little 3-way toggle switch on the Intake Actuator to move just the Intake valve from the Spa position to the Pool position.. So, it would shuck water from the pool and return the water to the spa.. In this test mode, if the pump filled with water it would indicate that for some reason, when sucking water from the spa, that there is some issue with the water getting from the spa drain and into the pump.. Maybe a clog or air leak.. When done with the test, move the toggle switch back to its original position.
Thanks,
Jim R.