Adjusting Hardness

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

In most areas of the country a minimum of 150 ppm and ideal level of 200 - 400 ppm of hardness is recommended. The only practical way to lower hardness is to drain some water from the pool or spa and refill with water lower in hardness.

Once you determine the hardness concentration, calculate how much you wish to add and find this number in the left-hand column. Match this with the volume of water in the pool or spa, listed at the top of the table. Be careful when mixing calcium chloride with water since this can generate a significant amount of heat. Allow the water to circulate 4-8 hours after the chemical is added and then check the hardness.

Raising Hardness with Calcium Chloride
Notes:

A significant amount of heat can be generated when mixing calcium chloride in water. Follow manufacturer's recommendations carefully.

100 Gallons 1,000 Gallons 5,000 Gallons 10,000 Gallons 20,000 Gallons 50,000 Gallons

To Raise ppm

Tsp oz Lbs oz Lbs oz Lbs oz Lbs oz Lbs oz
10 1 0 2 0 10 1 4 2 7 6 2
20 2.5 0 4 1 4 2 7 4 15 12 4
30 3.5 0 6 1 13 3 11 7 6 18 7
40 5 0 8 2 7 4 15 9 13 24 9
50 6 0 10 3 1 6 2 12 4 36 11
60 1.2 0 12 3 11 7 6 14 12 36 13
70 1.4 0 14 4 5 8 12 17 3 42 16
80 1.6 0 16 4 15 9 13 19 10 49 2
90 1.8 1 2 5 8 11 1 22 2 55 4
100 2 1 4 6 2 12 4 24 9 61
Metric:
 

400 Liters

4000 Liters

20000 Liters

40000 Liters

80000 Liters

200000 Liters

ppm

Kg

g

Kg

g

Kg

g

Kg

g

Kg

g

Kg

g

10

0

10

0

60

0

290

0

590

1

180

2

940

20

0

10

0

120

0

590

1

180

2

350

5

880

30

0

20

0

180

0

880

1

760

3

530

8

820

40

0

20

0

240

1

180

2

350

4

700

11

600

50

0

30

0

290

1

470

2

940

5

880

14

700

60

0

40

0

350

1

760

3

530

7

60

17

640

70

0

40

0

410

2

60

4

120

8

230

20

580

80

0

50

0

470

2

350

4

700

9

410

23

520

90

0

50

0

530

2

650

5

290

10

590

26

460

100

0

60

0

590

2

940

5

880

11

760

29

400