Hmm. OK, here's what I know and what I don't know.
1- I know the filter is completely clean and the flow isn't being obtructed there, at least. It's a CalSpa QUEST 2000 with an Ozone cartridge that I've never replaced. I've not even looked inside the blue box that contains the cartridge. Could that be a factor here?
2- Pressure switch... I think I know where that is and I've adjusted it manually before. It's on the right side of the heater and has a button in the middle and a dial I can turn to adjust activation pressure. I forget the units but I believe the scale was from 1-5 or so. Should I simply adjust that setting? I notice the switch activates when I turn the jets to high, but I've not seen it do anything else at any time.
If the pressure switch is bad, how would I know? How do I test it?
3- Flow switch... not sure what it is or where it is or what it does. I'm pretty sure they are not the same thing as "safety suction switches" so I'll need some guidance concerning their nature, position, and testing/adjusting of flow switches.
4- I believe "safety suction switches" are different and I had to had to disconnect them last year because the tub would not turn on at all (error code SF or something) and I was told they are unnecessary. Worse, I accidently broke the right one off and had to seal it with a golf tee and plenty of clear silicon caulk. It was quite a trick with the tub full and water coming out, but I got it done. I wanted to do something I knew I could un-do if necessary and it's held up just fine.
But, if these are indeed flow switches, I would have to replace one or both and try to find out why I'm getting an error with them connected.
Whlie the following isn't the actual post I took advice from, it fits my error code problem:
"I got that error and was having a hell of a time with it. Called CalSpas and got zero help, other then giving me a number to a local dealer. Called the dealer and he was a great help and told me how to fix the problem in a flash. The SF safety system is useless and only required in California. This is what you have to do. If you look at your pump(s) you will see a blue cover over a switch on the pipe by the pump(s). Follow the wire(s) into the control box...make sure power is off! Unplug the connector the wires are connected to. Problem fixed...error gone! Now look at those blue covers and see if one of them is leaking. If one of them is simply unscrew it from the pipe and plug the hole with a towel and duct tape. Buy a plug at the hardware store...either plastic, brass or cooper. DO NOT USE GALVANIZED and remove the duct tape and screw in the plug. Your tub will now be as good as new and you will never get locked out with a SF error again."