See for example - http://poolservicestech.com/tag/reverse-osmosis/

RO is a boom-bust business. When water is cheap to replace, it can't compete. However, with recent price increases here in municipal water rates, RO is starting to come on par with water replacement. As long as the company you choose uses industrial grade equipment (not the under-the-sink garbage you get at HomeDepot), 80% recovery is very achievable. It's all dependent on the water pumps and pressure you use, the higher the pressure, the better the efficiency. Typical filter membrane pressure is anywhere from 250-300psi. Normally these companies have to back a truck up into your yard and the process can take a couple of days depending on water volume. High pressure, industrial units typically process a few thousand gallons per day. Desalination typically requires several filter units cascaded together as a single RO membrane can only fractionally change the salt level.

Yikes! A chemical that eats CYA?!? Not sure I want that in my pool