Pool/Spa Combo, Salt and Solar --- Yikes!

[waterbear]

a schematic of your plumbing system would be helpful to figure out what is happening. I have a pool spa combo and it is plumbed in such a way that I can have the suction and returns go to the pool only, the spa only, or run in spillover with the returns going to the spa and the suction in the pool. My Goldline Aqualogic will chorinate in any of these settings (and allows me to select differant chlorine outputs and pump run times for for the spa only mode vs pool only or spillover and my heatpump will bring the spa to a higher temp when in spa only mode because the Aqualogic automation allows me to select different thermostat settings for each. It will work exactly the same if I had solar insted of a heatpump. Do you have a separate pump for running in spa only mode or are you selecting the different operating modes with valves or actuators? It seems that the problem you are having might stem from the way the system is plumbed. There is more than one way a pool/spa combo can be plumbed and some offer more flexibility than others. More info would be useful to help determine what is going on. One possible solution (although a pricey one) might be an automation system that will allow you to select these different settings for the different modes of operation if the equipment that you currently have cannot.