The Arizona State rules for operation of pools (Click to see rules) provide the important rules that Golden Vista must meet in the operation of the two  pools and spa.   The water must meet a disinfection standard of either:
1. “A free chlorine residual between 1.0 and 3.0 ppm in the pools and 3-5 ppm in the spa as measured by the N, N-Diethyl-p-phenylenediamine test” (hereafter referred to as “DPD Test”), or
2.  An oxidation-reduction potential equal to or greater than 650 millivolts (hereafter referred to as “ORP Test”) for both the pools and spa.
 
Which test is best?  For automatic control, the ORP test is used.  A good  article concerning ORP is “ORP Testing and Chemical Automation for Swimming Pools and Spas.” 

A study by Dr, Brown of the Oregon Department of Health conducted over 20 years ago (mentioned in the above article) shows that ORP is a better measure of the sanitation level of the pool. A comment about this study is quoted from an online article “Controller Concepts: ORP and Oxidation—Part I” on the Professional Pool Operators of America website:

“A well-known study performed by Dr. Jim Brown of the Oregon State Health Department about fifteen years ago made it crystal clear that ORP is the qualitative measure of choice for sanitarians or operators evaluating the safety of pool water and the efficacy of the sanitizer. In this remarkable study, thirty public spas were examined for all normal pool variables plus plate count (bacteria density) and, finally, ORP. Extremes showed up in pH from 5.7 through 8.3, combined chlorine from 1.4 to 34 ppm, free chlorine from 0 to 30 ppm, cyanuric acid (what’s it doing in a spa??) from 0 to 1,300 ppm, plate counts from 0 through 15,000, and even Pseudomonas up to 12,400! The only correlation that stood up throughout the study was the relationship between ORP and the presence of pathogens. Virtually no plate count existed in the spas where ORP values were found to be above about 630 millivolts, while lower values, no matter the free chlorine residuals present, all had dangerous or near-dangerous levels of pathogenic life (bugs!). Among the unsafe pools in the study, chlorine residuals bore no resemblance to the plate-count values. Even when the free chlorine was as high as 4 ppm, a significant plate count existed because the ORP in that spa was 537 mV. The pH was 6.9, so why was the ORP so low in that spa’s water? Excessive cyanuric acid was the culprit, as was the case in all but two of the thirteen spas exhibiting ORP levels at or below 630 mV. No matter the reason for low ORP, however ? low sanitizer, CYA, high pH, chloramines ? you could count on unsafe water and eventual turbidity.”

In 2006, I convinced the Board of Directors to spend $12,000 to install measuring and control equipment on the small pool.  Here is a link to an article that I wrote for the Resort's April 2006 newsletter regarding the chlorination system on the small pool. 
This installation has not performed as I envisioned.  Part of the problem is that the measurement system that came with the controller has not always been accurate--maybe because of equipment limitations, maybe because of the sensors getting dirty, and/or because of calibration.  Also the system does not allow logging of the values. 
A second issue is that the chlorinator system may have been under-sized.  I like the  following comment about sizing that is quoted from an online article “Controller Concepts: The #1 Rule” on the Professional Pool Operators of America website: "The #1 rule: Chemical feed systems must be big, big, big! If you are considering automation yet have manual feeders that, on busy days, need to run constantly – barely keeping up with the demand – you cannot automate. Pumps for both chlorine and pH corrector must be OFF more than they are ON when being cycled by a controller. On an average, they should be off three times more than they are on."

PROPOSED PLAN

My proposed plan for improving the chemical balance of the water in the two pools and spa is as follows:

1. Demonstration PHASE for Measurement:  On March 15, 2011, the Board of Directors approved $4,000  from the Capital Improvements Reserve Fund  for the DEMONSTRATION PHASE.  The demonstration phase involves installing ORP on the two pools and Spa together with their associated transmitters.  Data from the transmitters will be collected on a computer and stored.  Click here for EXAMPLE report of data on computer. 

2.  Measurement Project:  Approximately $12,000 will be needed to complete the measurement portion of the project.  This  involves installing pH and temperature sensors on the two pools and Spa together with their associated transmitters.  Data from the transmitters will be collected on a computer and stored.

2.  Control Project:  The second step is install equipment and control the chemicals.  First, we will need to demonstrate that we can control the small pool.  This may require adding some equipment.  After the small pool, then we would put similar control equipment on the large pool and spa. 

3. Data on Web: At some point, I believe the pool data should be on he website for our residents to know that the pools are in control.