What about outside air for ventilation?

Pools release chemicals into the air including odors from the oxidation of organic compounds produced through human activity. Outside air is necessary to dilute these contaminants. We recommend up to 0.5 cfm per square foot of outside air for ventilation and an equal amount of exhaust to provide removal and balanced pressure in the pool area. In some cases a slight negative pressure (more exhaust than supply) may be desirable in order to minimize pool odors migrating into adjacent spaces. Aqua-TEC units are designed to bring in outside air at up to 30% of rated cfm, usually more than enough to meet the need. The outside air is introduced after the evaporator and before the reheat condenser, providing steady operating conditions for the refrigeration system and thus superior control of space conditions. A separate exhaust fan is required and may be operated in conjunction with an optional motorized outside air damper in the Aqua-TEC unit to provide ventilation only when the natatorium is occupied.