The pH level is one of the most important elements relating to swimming pool water balance.
For the safety and comfort of swimmers, it should be tested and subsequently corrected at the minimum of once a week.
It is important to have a habit of checking pool’s chemicals to ensure safety, however life’s events get in the way. I find this is particularly true over winter when the pool is not in use.
My goals for this project are;
- Stage one the measurement and control of the pool Ph. level.
- Stage two the measurement and control of the chlorine level, more on that later
The pH of the human body is comfortable is around the 7.2 level which is going to be the set point for this system and it the recommendation of the pool company.
If the Ph. 7.0, the swimming pool water will become acidic.
A low pH reading can cause my swimming pool concrete lime to dissolve over time as well as substantial corrosion of any metals including filters, valves, rails or pumps as well as itchy or dry skin.
On the other end of the spectrum, high pH can create scaling or calcium build up on pool surfaces, waterline and accessories, cloudy water, clogging of filters, and drop in disinfection potential of chlorine resulting in algae growth and a generally unhealthy place to be.
Unfortunately I have experienced this over a winter. Aside from a green pond in spring, the only way I found to remove the resulting calcium icicles was a wire brush and the use of goggles & snorkel.
Good exercise, however I’d rather a brisk walk!
After looking at commerial solutons to my problem, I found that they fall into the $2000 ( for a closed loop control system). Surely I can put one together for less ?
And, oh one more reason…….
I get to tinker with various micro controllers, sensor's motors AND I can justify the purchases to my wife 
Where next ?, hunting for sensor & chemical delivery.