Fresh water is neutral at a pH of 7. On the acid side, a lemon 3, and pool acid 0. On the alkaline side, soap is about 10 and drain cleaner is 14. For swimming, the most comfortable pH is about 8 to 8.5, with a workable range from about 7 to 9 – anything else will cause irritation to the skin and eyes.
The basic problem in managing water chemistry is that the natural pH of most pools, other than fibreglass, is about 8.0 – 8.5. This is where the pool water is naturally self-balancing. Pools rise quickly to this pH because alkali in the surface finish of the pool leeches into the water. In addition, liquid chlorine self-decomposes to sodium hydroxide (drain cleaner), further increasing the alkalinity when added. Salt chlorination is also alkaline. Due to all of these, the alkalinity rises in most pools until atmospheric carbon dioxide dissolves in the water, adding acidity till the pool finds a balance.
Unfortunately, at this typical pH 8.0-8.5, the chlorine in the water converts to a form that is a poor sanitiser. This means that you may need 10 or more times as much chlorine at 8.5 as you would at pH 7.2 and you may still get a green pool as well as unpleasant side-effects such as sore eyes and chlorine smells. If you have a salt chlorinator, you will have to run it and the energy-hungry filter pump, much longer hours.
There are two basic ways to do this. The conventional approach used for the last 60 years, is to add pool acid to drive the pH to 7.2-7.6 and re-convert the chlorine in the pool water to a more active sanitiser. Unfortunately, the pool water rapidly becomes alkaline again in a few days to a week. The pool effectively yo-yos between too much and too little chlorine between acid additions. To try to deal with, especially when you don’t have sensor-based control systems, quite large and expensive quantities of buffer, stabiliser, calcium lifter, algaecide and pool (hydrochloric) acid need to be added regularly with regular water testing.
Pooled’s Advanced Water Chemistry operates at a higher, more natural pH than conventional chemistry and largely eliminates the need to add acid, buffers, calcium and other chemicals. The result is incredible feeling pool water.