Adjusting Chlorine

It is recommended that dry chemicals first be mixed into a generous amount of pool water in increments of about two pounds, and the predissolved mixture be distributed evenly around the pool unless directed otherwise.

Precautions

Best results are obtained by predissolving granular chlorine products, especially if you have a vinyl pool. Trichlor is erosion fed through skimmers or floating passive feeders. Simply add one Trichlor stick or puck. Do not try to break pucks, since these could burn hands.

The disinfectant form of chlorine is "free residual chlorine." It is also known as “free available chlorine” or “free chlorine” and all terms refer to the concentration of hypochlorous acid and the hypochlorite ion in equilibrium concentration in the pool water. It is strong and safe when used properly and is still the most popular form of disinfection. There is much material available on the techniques of chlorination and "breakpoint chlorination" in particular; and it is excellent practice to attain breakpoint before the first chlorine measurements are taken each day. Breakpoint chlorination means that all of the chlorine is available as free chlorine. This is achieved by adding sufficient chlorine to burn out all the combined chlorine, so that free chlorine equals total chlorine.

The higher the pH above 7 the less the disinfection power of free chlorine. pH needs to be properly controlled in a swimming pool and spa pool when chlorine is used and automatic adjustment is recommended to levels between 7.2 and 7.8.

Raising Chlorine 1 ppm
Notes:

Routine shock treatments may require a 10 ppm dose while algae problems may require even higher doses. Consult product label before adding any chemical products.

  100 Gallons 1,000 Gallons 5,000 Gallons 10,000 Gallons 20,000 Gallons 50,000 Gallons
Tsp oz oz oz oz oz
Sodhypo* 1 1 oz 7 oz 13 oz 1.5 pt 2 pt
Lithium 1/4 0.4 2 4 8 19
Calhypo 1/10 0.2 1 2 4 10
Dichlor† 1/10 0.2 1 2 5 12
Dichlor‡ 1/10 0.2 1 2 4 11
Trichlor 0.1 1 1.5 3 7
Metric:
 

400 Liters

4000 Liters

20000 Liters

40000 Liters

80000 Liters

200000 Liters

grams

grams

grams

grams

grams

grams

Gas

0.4

5

20

40

80

200

Lithium

1

10

55

115

230

570

Calhypo

1

5

30

60

125

310

Dichlor†

1

5

35

70

145

355

Dichlor‡

1

5

30

65

130

325

Trichlor

0.4

5

20

45

90

220

Sodhypo*

3

35

165

335

665

1665

*This is a liquid and the calculation assumes 1 liq. oz. (10%) = 1 dry oz.
† dihydrate form
‡ anhydrous form (see product label)