Carl, I do understand Mark's point. Mark has been terrifically helpful over the years with the information he has passed on to me. Without that information it would have taken a lot longer and cost a lot more in research.

I know at the moment it doesn't seem logical to you to run 24 hours a day but rather than go around in circles can we put some facts and figures down? I don't know the cost of electricity where you are so that would be useful.
How much electricity per hour do you use on low speed?
Do you know your actual flow rate on low?
What is the flow rate needed to run your heating (min flow)

If the electrical energy used for 24 hour running is less than you use for 12 hour running that would still be a saving, yes?

On a separate note: I didn't know running low TA levels was ok on the pool forum, I have been doing the same over in the UK and France as it didn't make any sense to run at a high TA (Vinyl pools only) currently run at TA 40ppm with very stable pH. I have a customer who is running around 22ppm TA as their water is really soft in that area still no bad effects and very stable pH.

If you would prefer to move the thread to the china shop I am OK with that if it's the proper place but I don't just want the topic to gather dust.