Your SWC seems to be working overtime, and your CYA is holding on to the Cl produced like grim death!

Try bringing the CYA down to the SWC manufacturer's specs, and you should get a better perspective of what the SWC and the CYA can do. You will then be able to lower your SWC output setting, and increase the cell life. If it means draining water, then I would do so. 150 ppm seems way too high for a SWC to handle, even at 100%.

Hope this helps.

Pat