13
Rev. K 5-31-06
P/N 470880
Maintenance (contd.)
CHEMICAL BALANCE (contd.)
pH
- The term pH refers to the acid/alkaline balance of water
expressed on a numerical scale from 0 to 14. A test kit for
measuring the pH balance of your pool water is available from
your local pool supply store; see Table 1.
Muriatic Acid has a pH of about 0. Pure water is 7 (neutral).
A weak Lye solution has a pH of 13-14.
RULE:
7.4 to 7.6 is a desirable pH range. It is essential to
maintain correct pH; see Table 2.
If pH becomes too high (over alkaline), it has
these effects:
1. Greatly lowers the ability of chlorine to destroy bacteria
and algae.
2. Water becomes cloudy.
3. There is more danger of scale formation on the plaster or
in the heat exchanger.
4. Filter elements may become blocked.
If pH becomes too low (over acid) the following
conditions may occur:
1. Excessive eye burning or skin irritation.
2. Etching of the plaster.
3. Corrosion of metal fixtures in the filtration and
recirculation system, which may create brown, blue,
green, or sometimes almost black stains on the plaster.
4. Corrosion of copper in the heater, which may cause
leaks.
5. If you have a sand and gravel filter, the alum used as a
filter aid may dissolve and pass through the filter.
CAUTION
Do not test for pH when the chlorine residual is
3.0 ppm or higher, or bromine residual is 6.0 ppm
or higher. See your local pool supply store for help
in properly balancing your water chemistry.
RULE
: Chemicals that are acid lower pH.
Chemicals that are alkaline raise pH.
ALKALINITY High - Low:
"Total alkalinity" is a measurement of the total
amount of alkaline chemicals in the water, and
control pH to a great degree. (It is not the same as
pH which refers merely to the relative alkalinity/
acidity balance.) Your pool water's total alkalinity
should be 100 - 140 ppm to permit easier pH
control.
A total alkalinity test is simple to perform with a
reliable test kit. You will need to test about once a
week and make proper adjustments until alkalinity
is in the proper range. Then, test only once every
month or so to be sure it is being maintained. See
your local pool dealer for help in properly balancing
the water chemistry.
pH Chart
Table 1.
Strongly Acid
Neutral
Strongly Alkaline
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
7.2
6.8 7.0
7.4 7.6
7.8
8.0 8.2 8.4
Add Soda
Ash or
Sodium
Bicarbonate
Add Acid
Marginal
Ideal
Marginal
pH Control Chart
Table 2.
