Maximum FAC Concentrations

Maximum FAC concentrations shall not exceed 10.0 PPM (MG/L) at any time the AQUATIC VENUE is open to bathers.

FAC levels should be consistent with label instructions of the disinfectant. All POOL and SPA disinfectants must be registered by the U.S. Environmental Protection Agency (EPA) under the Federal Insecticide, Fungicide and Rodenticide Act. The MAHC welcomes input and supporting data for establishing upper limits. At this time, the MAHC requires FAC maximum levels to be consistent with label instructions. An upper limit of 10 PPM (mg/L) has been chosen to ensure operators can still reasonably measure FAC. Issues have arisen with extremely high levels being added when poorly trained operators cannot measure FAC and continue adding disinfectant without realizing the test is bleaching out rapidly. EPA has not approved any POOL product use above 4 PPM (mg/L) FAC or SPA product use above 5 PPM (mg/L) FAC when BATHERS are present. The maximum FAC level approved for POOLS is consistent with EPA’s Maximum Residual Disinfectant Level (MRDL) of 4 PPM (mg/L) for drinking water. No data was identified suggesting health risks from FAC levels at, or even significantly above, these levels. The EPA MRDL and the World Health Organization’s drinking water guideline value for CHLORINE (5 PPM (mg/L)) are based on drinking water studies that found no adverse effects related to CHLORINE³³³. Use of high levels of CHLORINE as a “shock dose” when BATHERS are not present may be part of an overall water quality management strategy. Periodic shock dosing can be an effective tool to maintain microbial quality of water and to minimize build-up of biofilms and inorganic chloramines. For BATHER re-entry, FAC levels shall be consistent with label instructions of the disinfectant. Salt water (saline) chlorination systems generate and deliver a CHLORINE disinfectant on-site directly into POOL water. While cell size and configuration of these systems may differ depending on the manufacturer, the principles of their operation remain the same. Sodium chloride is added to balanced POOL water to establish a saline solution, which flows through the electrolytic cell. A low voltage electrical charge is passed through the saline solution and the current breaks the sodium and chloride bonds resulting in the formation of CHLORINE gas, hydrogen gas, and sodium hydroxide: 2 H20 + 2 NaCl (aq) ? Cl2 (g) + H2 (g) + 2 NaOH The hydrogen gas is dissolved in the water and eventually vents to the atmosphere. The CHLORINE gas then dissociates into hypochlorous acid (HOCl), which provides a residual of FREE AVAILABLE CHLORINE (FAC): Cl2 (g) + H20 ? HOCl (aq) + HCl (aq) Salt water chlorination units should be sized appropriately to maintain minimum FAC levels during maximum load periods. The units should ideally be controlled by an ORP controller. Operators must still test the FAC residual of the water to ensure that the cell is producing adequate CHLORINE for the POOL. However, a separate chlorinating product may be needed to provide a sufficiently high FAC level for shock treatment or remediation following a fecal accident. MONITORING and maintaining the pH, total alkalinity, and TDS of the water in the POOL is important. Salt water POOLS intentionally have high concentrations of sodium chloride. The sodium chloride will contribute to TDS, but will not cause decreased disinfectant efficacy or cloudy water. Electrolytic cells do wear out and need to be replaced. The life of the cell depends upon how many hours the cell operates each day, the pH of the water, and the calcium content of the water. The cells have to be cleaned to remove scale build-up. The systems usually utilize reversal of the polarity on the cells to minimize the scale formation, but eventually the cell will have deposits that require the cell to be removed from the plumbing and soaked in an acid solution. The cells are also vulnerable to damage if they are operated in conditions of lower than recommended salt residuals or in water that is too cold. The systems have sensors and cut-offs to prevent this damage, but operators must be sure to monitor the unit to recognize when there is a problem.