Starting to mull over the idea of the Hayward sense and dispense kit http://www.hayward-pool.com/webapp/w...ductId=1009530

It strikes me as odd that the system uses C02 to reduce PH according to the manual? Is adding C02 a legitimate method for controlling pH? I've never seen it mentioned anywhere else.

From an advertisement for this product:
The first kit senses pH and ORP levels and dispenses a self-renewing supply of pure chlorine generated from salt. pH dispense can be achieved using the second kit, which includes a manifold that connects to a CO2 tank. CO2 is highly effective in lowering pH.