Problem: I have an Aqualink / RS6 that can't be set below 38F with current software for freeze protection, causing the pump to run many extra hours per night in winter.
Solution: Air temperature is read from a thermocouple which can be "spoofed" by simply placing a shunt resistor of determined value across the thermocouple terminals. To determine the shunt resistance for a 33F temp set point instead of 38F, I used a 1MOhm potentiometer to plot shunt resistance against temp readings on my equipment and software (473kOhm=+1F, 314kOhm=+2F, etc). I switched power off, screwed in the selected value shunt resistor into the PCBoard terminals that the thermocouple uses, and switched power back on.
To be on the safe side, I put an Aluminum pan with 1/2in of my pool water next to the pipes to confirm the pump indeed turns on before freezing. The display will read higher air temps than actual while the shunt resistor is in, but it can be set to not be displayed on my RS6.