GCH,
Most spas are supposed to spill over into the pool...
On the suction side of your plumbing:
You have two pipes coming into your pump through the "Intake" valve. The Intake valves lets you select water from the Pool or water from the Spa
When you want the Pool on, you need to point the OFF tab to the Spa pipe. This turns off the Spa line and turns on the Pool line.
When you want the Spa on, you need to point the OFF tab to the Pool pipe. This turns off the Pool line and turns on the Spa line,
On the Return side of your pluming:
After the filter the water goes to the "Return" valve. This valve sends water back to the Spa or back to the Pool.
When water goes back to the Pool, it comes out of the eyeballs in the side wall of the pool.
When the water goes back to the Spa side there is another valve that sends water to the spa returns (jets)
When in the Pool mode, I also
suspect that some of this water comes up the pipe marked "Cascade" and when the cascade valve is open, it flows into the spa causing it to spillover into the pool. You should be able to adjust the spillover with the cascade valve.
Your Intake and Return valves should always be in the same mode. Both in the Pool mode or both in the Spa mode. In your pics, the Intake valve is in the Pool mode, but your Return Valve is in the Spa mode. This is why the spa is overflowing and you can't control it.
Put the Intake and Return valves both in the Pool mode and see what happens. I suspect your spillover will stop.. Adjust the cascade valve and see if it makes the spillover come on...
Put them both in the Spa mode and see what happens. When in the Spa mode, the spillover should stop.
Thanks,
Jim R.