Swimming
Pool Water Testting
pH
pH is a measure
of the amount of hydrogen ions, that are in solution. The pH scale goes
from 0 to 14. Zero is very acidic and 14 is very basic. A reading of 7.0
is nuetral. pH affects the swimming pool water, far more than any other
parameter. It afects the efficiency of the sanitizier, as well as the
overall balance of the pool. pH is measured using a chemical known as
phenol red, and the color produced by adding the phenol red to a sample
of the swimming pool water. The color produced is compared to colors from
known concentrations of hydrogen ions. Alternatively, pH can be tested
using test strips. The test strip is dipped into the pool water and compared
once again to known standards. Electronic meters are also available for
measuring the pH, the pH is read directly from the meter, without comparison
to a known color. Acid demand is the amount of acid needed to be added
to a pool to lower the pH to the desiredd range. Base demand is the amount
of basic material required to rais the pH to the desired level. To lower
the PH, usually dry acid is used, sodium hydrogen sulfate (pH decreaser),
to raise the pH, usualy sodium carbonate(pH increaser) is used. If the
ph is only slightly low, Sodium hydrogen carbonate can be used (Alkalinity
increaser). Acceptable pH values are between 7.2-7.8
Alkalinity
Total
alkalinity is actually the measure of hyroxide and carbonate ions that
are present in the water, expressed in units of parts per million (ppm).
Alaklinity affects the pools water balance, as well as the acid or base
demand. Alkalnity acts as a buffer to prevent the pools pH from bouncing
up and down. Acceptable values for alkalinity are between 80-120 ppm.
Alkalinity is usually determined by titration. Titration is performed
on the water sample, by adding a dye to the water, that changes, when
a second chemical (an acid) is added dropwise, until a color change is
noted. Alternatively test strips are available to dip and read. As a general
rule 25 ounces or muriatic acid or two pounds of PH reducer (powder),
will lower the Alkalinty 10 ppm, in a 10,000 gallon pool. Remeber to allow,
suffiiceint time for the chemicals to mix, before retesting, typically
1 cycle of the pump is sufficient. To raise alkalinity, pH increaser,
sodium carbobate(also increases pH) or alkalinty increaser, sodium hydrogen
carbonate can be used. Until experience is gained it is suggested to use
the alkalinity increaser.
Hardness
Is
the amount of calcium and magnesium that is present in the water. Water
below 60 ppm is soft water and water greater than 120 is said to be hard.
Water does not like to be soft. Water that is soft will attempt to become
hard, by dissolving minerals from the enviornment, typically the pool
wall. Water hadness is tested in a manner similiar to that already described
for alkalinity. Alternatively test strips can be used. Water hardness
should be in the range of 150 to 250 ppm. It is increased by adding calcium
increaser (calcium chloride) to the water, reducing calcium hardness can
be accomplished by dilution with water, with less hardness than is currently
in the pool. It can also, be reduced chemically, using Tri-sodium Phosphate,
but this should be left for a pool professional. Calcium levels can increase
by prolonged use of calcium based chlorine products. Read the label, if
it says calcium hypochlorite ad you calcium levels are high, swithc to
another form of chlorine
Total
Dissolved Solids
Total
dissolved solids or TDS is a measurement of all the materials that are
dissolved in the pools water. Higher levels of TDS (above 2000), can cause
strange phenomena to occur, for example algae growth, where an obviously
high present of chlorine is available. TDS is measure using a conductivty
meter. Lowering of the TDS is accomplished by replacing the existing water
with water that is low in TDS. if TDS is high avoid the use of chemicals
that are increase the TDS. An example of this is Liquid Chlorine.
Copper
Testing
Copper
is introudced into pool water from copper based algaecides or from water
that is extremely corrosive and dissolves components that are part of
the pool, such as brass valves, impellers or heater components. Copper
can cause staining of the pool surface, usually a turqoise stain, swimmers
can come out of the pool with green hair or blue fingernails. The standard
test for copper is colormetric, chemicals are added to a sample of pool
water, if copper is present a color is produced and compared to known
standards. Copper can be removed from pool using chemicals called seqesting
agents.
Iron
Testing
Low
levels or Iron (0.1 ppm) can give water a bitter medicinal taste, higher
levels can cause staining, which is often black or rust colored. Iron
can be introuduced into the pool from the fill water and if the water
is corrosive, from the piping and other equipment present in the pool.
The standard test for Iron is colormetric, chemicals are added to a sample
of pool water, if Iron is present a color is produced and compared to
known standards.
Cyanuric
Acid
Cyanuric
acid is the conditioner that is added to the pool, to prevent the suns
rays from breaking down the chlorine faster that if the conditioner was
not present. Typicall levels of Cyanuric acid are 40 ppm, it can increase
by the use of stabilized products such as dichlor or Trichlor sanitizers.
Chlorine
Testing
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