Minnesota Administrative Rules

4717.1750 POOL WATER CONDITION.

Subpart 1.

Maximum water temperature.

The water temperature in a pool must not be more than 104 degrees Fahrenheit.

Subp. 2.

Test kits.

Each pool must have the testing equipment specified in this subpart:

A.

a DPD (Diethyl-P-Phenylene Diamine) test kit to measure the concentration of disinfectant in water, accurate within 0.1 parts per million;

B.

a phenol red pH testing kit accurate to the nearest 0.2 pH unit;

C.

a test kit to measure alkalinity using the methyl orange or equivalent method; and

D.

where cyanuric acid is used, a test kit to test cyanuric acid concentration.

Subp. 3.

Disinfection residual.

When in use, a pool must be continuously disinfected with a chemical that imparts an easily measured, free available residual.

A.

When chlorine is used, a free chlorine residual of at least 1.0 parts per million must be maintained throughout the pool.

B.

When bromine is used, a bromine residual of at least 2.0 parts per million must be maintained throughout the pool.

C.

The disinfectant concentration in an operating pool must not exceed ten parts per million for chlorine and 20 parts per million for bromine.

D.

If other halogens are used, residuals of equivalent disinfectant strength must be maintained.

E.

If the concentration of combined chlorine residual exceeds 0.5 parts per million, the pool must be superchlorinated or treated to reduce the concentration of the combined chlorine residual to not exceed 0.5 parts per million.

Subp. 4.

Disinfection of spa pools.

The disinfectant residual in a spa pool must be at least 2.0 parts per million for free chlorine and 4.0 parts per million for bromine throughout the pool when in use.

Subp. 5.

pH.

Water in the pool must be maintained with a pH of not less than 7.2 and not more than 7.8.

Subp. 6.

Alkalinity.

The alkalinity of the water in the pool must be at least 50 parts per million.

Subp. 7.

Water clarity.

Whenever the pool is open for use, the pool water must be clear enough so the bottom drain is easily visible.

Subp. 8.

Use of nontoxic chemicals; chemical container security.

Chemicals used to control water quality must not impart toxic properties to the water. All containers used for chemicals must be kept in a secure location, inaccessible to pool users, and properly labeled and stored according to the manufacturer's instructions.

Subp. 9.

[Repealed, 46 SR 175]

Subp. 10.

[Repealed, 46 SR 175]

Subp. 11.

Use of cyanuric acid.

A.

Use of cyanuric acid in any new indoor pool is prohibited after February 23, 2022.

B.

Use of cyanuric acid in any existing indoor pool is prohibited after February 23, 2024.

C.

Use of cyanuric acid in any pool requires testing and recording of the cyanuric acid level at least once a week.

D.

Where cyanuric acid is used to stabilize chlorine, the concentration of cyanuric acid in the pool must not exceed 100 parts per million.

Statutory Authority:

MS s 144.05; 144.12; 144.1222; 144.123; 144.222; 145A.02; 157.01

History:

19 SR 1419; 19 SR 1637; 40 SR 1646; 46 SR 175

Published Electronically:

May 4, 2022