Hayward Sense & Dispense

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:

Quote:

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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.

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CO2 is a legitimate method to control pH and is mostly used in a commercial pool environment. It is naturally around 7.0 pH, so that accidental overdosing of CO2 won't drop the pH like Muriatic Acid would...which makes it safer to use and alot less acidic. Carbonic Soda or Beverage Suppliers would deliver these to commercial sites in heavy tanks (up to 200 lbs).
The things to consider with CO2 in a residential environment, where do you go to refill your CO2 tank (since these suppliers do not typically deliver to residential homes, you would have to go get your tank refilled at their location)? What method is used to inject the CO2 (not using the proper injection fitting or dispersion stone, will waste alot of CO2)?

I believe Hayward also offers a Muriatic Acid tank and pump option, like the Pool Pilot Total Control system does. We've found Muriatic Acid to be easier to get than CO2.

I experimented with CO2 injection in the late 80's -- even built my own injection system using German fused glass bubblers. The problem I found is that when you use CO2 to control pH, you get uncontrolled carbonate (-HCO3 + =CO3) build up. This is a result of using CO2 to form carbonic acid (H2CO3) which, as it lowers pH, is 'converted' to carbonates.

In general, I found it to be inefficient and troublesome, compared to muriatic acid. Shortly after that, I discovered how to keep muriatic acid from fuming, and I no longer had any reason to mess with CO2. I've since seen it used on a 700,000 pool (not a pool I was servicing) in conjunction with a Strantrol ORP/pH controller, at huge expense and constant problems.

Ben

PS. My very strong impression is that Hayward's new focus on technology and the commercial pool market is almost totally marketing driven, rather than engineering driven. This does not inevitably produce flashy, but sucky products (a la Zodiac) but that's certainly the tendency.

Thanks for the input! Sounds like this isn't something I'll bother with.