W
ater Clarity
21
OC Hot Tubs Owner’s Manual
LTR50001045, Rev. N
8.2
8.0
7.8
7.6
7.4
7.2
7.0
6.8
6.6
Ideal pH balance
Add a pH
decreaser
Add a pH
increaser
pH too high
Too alkaline, causes
scaling
pH too low
Too acidic, causes
corrosion
pH
balance
120
140
160
180
100
80
Ideal TA balance
Add an alkalinity
increaser
Add an alkalinity
decreaser
60
40
20
TA too low
pH will fluctuate
wildly
TA too high
pH will be too high
and may be difficult
to stabilize pH
TA
balance
200
225
250
275
175
150
Ideal CH balance
CH too low
Causes equipment
corrosion
CH too high
Causes scale to
deposit on spa and
equipment
Add a calcium
hardness increaser
Dilute the spa
with soft water
125
100
75
CH
balance
Calcium Hardness is a measure of the total amount of dissolved
calcium in the water. Calcium helps control the corrosive nature of the
spa’s water. That’s why calcium-low water (commonly known as “soft”
water) is not recommended. It is very corrosive to the equipment, and
can cause staining of the spa shell.
If the CH is too high (commonly known as “hard water”), formation of
scale on the spa’s shell surface and equipment can result. You can use
a generic calcium remover to remove hardness from water. CH can
also be decreased by dilution – a mixture of 75% hard and 25% soft
water will usually yield a reading within the correct range. If soft water
is not available or practical for you, a stain and scale inhibitor should
be added to the spa water, according to label instructions.
If the CH is too low add CH Increaser.
Once the CH is balanced, it normally remains stable, although the addition of more water with a high or low calcium
content will raise or lower the CH reading of the water.
When the CH is within the recommended range, proceed to the next step.
Balancing the Calcium Hardness (CH)
8.2
8.0
7.8
7.6
7.4
7.2
7.0
6.8
6.6
Ideal pH balance
Add a pH
decreaser
Add a pH
increaser
pH too high
Too alkaline, causes
scaling
pH too low
Too acidic, causes
corrosion
pH
balance
120
140
160
180
100
80
Ideal TA balance
Add an alkalinity
increaser
Add an alkalinity
decreaser
60
40
20
TA too low
pH will fluctuate
wildly
TA too high
pH will be too high
and may be difficult
to stabilize pH
TA
balance
200
225
250
275
175
150
Ideal CH balance
CH too low
Causes equipment
corrosion
CH too high
Causes scale to
deposit on spa and
equipment
Add a calcium
hardness increaser
Dilute the spa
with soft water
125
100
75
CH
balance
Balancing the pH
The pH level is the measure of acidity and alkalinity. Values above
7.8 are alkaline; those below 7.2 are acidic. Maintaining the proper
pH level is extremely important for optimizing the effectiveness of
the sanitizer, maintaining water that is comfortable for the user, and
preventing equipment deterioration.
If the spa water’s pH level is too low, the following may result:
• The sanitizer will dissipate rapidly.
• The water may become irritating to spa users.
• The spa’s equipment may corrode.
If the pH is too low, it can be increased by adding sodium hydrogen
carbonate (pH/Alkalinity Up) to the spa water.
If the pH level is too high, the following may result:
• The sanitizer is less effective.
• Scale will form on the spa shell surface and the equipment.
• The water may become cloudy.
• The filter cartridge pores may become obstructed.
If the pH is too high, it can be decreased by adding sodium bisulfate (pH/Alkalinity Down) to the spa water.
NOTE: After adding sodium hydrogen carbonate or sodium bisulfate, wait two hours before testing the water for pH.
Measurements taken too soon may not be accurate.
It is important to check the pH on a regular (weekly) basis. The pH will be affected by the bather load, the addition of
new water, the addition of various chemicals, and the type of sanitizer used.
When the pH is within the recommended range, proceed to sanitation.
