The use of Oxidation-Reduction Potential (ORP) meters to assess recreation pool water quality is becoming more common. Traditional chemical based kits have been used for decades. Currently in the United States DPD (diethyl-paraphenylenediamine) chemical based test kits have become the standard. Other jurisdictions have established standards for ORP and many are either accepting ORP values exclusively or suggesting such testing as an adjunct to traditional chemical tests. We evaluated two hand-held ORP testers currently commercially available, to determine if ORP measurements might be an acceptable method for evaluating swimming pool and spa water quality. One-Hundred and Seventy-seven permitted commercial "pools" were tested with both traditional chemical tests and ORP measurements. Oxidation-Reduction Potential was evaluated by both the Oakton ORPtestr and Extech model 300 hand-held ORP testers. Both the Oakton ORPtestr (p-value <0.05) and the Extech model 300 (p-value<0.05) demonstrated a statistically significant correlation with traditional chemical measures of total and free chlorine residual. Cyanuric acid is used as a conditioner in pools to protect the loss of chlorine to the effects of the sun. Tests conducted in the present study correlating cyanuric acid levels to ORP did not show a significant correlation using either with the ORPtestr (p-value 0.437) or those collected with the Extech model tester (p-value 0.884) .
