Section 18 AAC 30.580 - Public spas(a) In addition to the other requirements of this section, public spas, including public hot tubs, must meet the standards set out in the April 1981 edition of Suggested Health and Safety Guidelines for Public Spas and Hot Tubs, published by the Centers for Disease Control, Public Health Service, United States Department of Health and Human Services, the requirements of which are adopted by reference in this chapter.(b) Continuous disinfection is required for spas built after June 4, 1983.(c) An automatic sensor control is required for disinfectant and pH.(d) A disinfectant other than chlorine or bromine will, in the department's discretion, be allowed under 18 AAC 30.955.(e) The free chlorine residual must be kept at a minimum of 2.0 mg/l and a maximum of 10 mg/l.(f) The pH level must be between 7.2 and 7.6 when the spa is in use.(g) The free chlorine or bromine residual and pH must be measured every two hours when the spa is in use.(h) Total alkalinity must be kept between 100 and 140 mg/l, and must be measured at least weekly.(i) An air circulation rate of at least six air exchanges per hour must be provided in the room containing the spa.(j) A spa, including a hot tub, must comply with 18 AAC 30.510(o) - (q), 18 AAC 30.545, and 18 AAC 30.550.(k) A spa, including a hot tub, with wooden interior surfaces is prohibited.(l) A spa, including a hot tub, must be completely drained whenever (1) the operator determines that the water requires replacement;(2) the number derived by dividing one-third of the total capacity, in gallons, of the spa, by the number of bather periods since the spa was last filled equals the number of days since the spa was last filled; or(3) the total dissolved solids reach 1,500 ppm; if this method is used, the total dissolved solids must be measured daily, with results recorded in the spa's log.Eff. 6/4/83, Register 86; am 12/23/93, Register 128A copy of Suggested Health and Safety Guidelines for Public Spas and Hot Tubs, adopted by reference in 18 AAC 30.580 may be reviewed at the central or regional offices of the Department of Environmental Conservation. A copy is also available from the Public Information Office, Centers for Disease Control, Atlanta, Georgia 30333, or from the Department of Environmental Conservation, 410 Willoughby Avenue, Suite 105, Juneau, Alaska, 99801-1795.