Most pool owners assess the well being of their swimming pool by what they can see: the clarity of the water and the appearance of its surfaces. As a service technician, you must be able to diagnose problems that can compromise the homeowners’ visual evaluation of their vessel. There are many
common issues that lead to staining in pools, and a few
Most stains and discoloration can be traced to improperly balanced
water. But even “perfectly balanced” pools have the
potential to contribute to these types of problems due to the
almost-daily influx of metals, minerals and other contaminants.
Oxidation also is a concern.
Common organic staining scenarios
Staining and discoloration can be broken down into two main
categories: organic and inorganic. Common organic causes include
scale, algae, “pink slime,” white water mold and vinyl
liner mold. The Langelier Saturation Index measures the
corrosiveness and neutrality, or scaling ability, of water. Water,
by nature, “wants” to be neutral or balanced. When pH
and/or total alkalinity are high, water cannot rid itself of either
of these two important components, but it can push out calcium.
Scaling is one unwanted by-product of this reaction.
When heavy rains combine with hot weather and low or no sanitizer,
algae in its many forms can become an issue. Mustard algae seems to
vanish easily when brushed, but will reappear quickly and continue
to spread if left unchecked. Black algae creates a protective
gelatinous coating. It also has roots, which can penetrate a
pool’s plaster, fiberglass or vinyl surfaces. Green algae can
first appear as a tinting of the water, which can rapidly transform
a pool into a veritable swamp if not treated. In addition to a
discoloration of the water, green algae also can produce rapidly
spreading stains throughout a vessel.
Pink slime actually is reddish bacteria that most of us have seen
on our showerheads. It can be introduced by rain, soil and
contaminated swimsuits — as can mustard algae — and can
rapidly grow in circulation pipes. Like pink slime, white water
mold grows in circulation piping. This contaminant resembles small
floating pieces of white tissue by the time it finds its way to the
pool water. Although not a surface stain, vinyl liner mold is a
fungus that grows underneath a vinyl liner, which is visible as a
shadow beneath its surface. Tannins, commonly associated with
trees, also can find their way into pools and create staining.
Common inorganic stains and discoloration
Inorganic troublemakers include scum-line buildup, cloudy or tinted
water and iron and copper stains. When suntan lotions, body oils,
make-up and dirt gather at the waterline, an unsightly scum-line
buildup can occur. It should be noted that organic contaminants
also can contribute, though they aren’t the main culprits. If
left unchecked, additional dirt and contaminants will more easily
adhere to an existing scum line, creating a snowball effect.
Cloudy water is a byproduct of unbalanced water, poor circulation
and poor filtration. Ironically, the response of then adding too
much clarifier can worsen existing cloudiness.
Metals such as iron, copper and manganese can produce a tinting of
pool water and serve as a warning of sorts that metals are present
in the system. All it may take is a shock treatment to plate the
metals from the water onto a pool’s surface, thus creating a
metal stain. Metal stains can also potentially be introduced from
well and municipal water, metallic equipment parts, pool chemicals
such copper- and silver-based algaecides, certain grades of salt
for chlorine generators, certain grades of chlorine, ionizers, lawn
chemicals and more.
Lesser-known causes of staining
Copper cyanurate, dubbed “purple haze,” can occur when
a high stabilizer level (above 100 ppm) combines with copper,
creating a purple precipitant. This purple stain is bright and
highly visible, often showing up on tile, spillways and pool
cleaners. If left untreated, copper cyanurate eventually will
adhere to all pool surfaces. Until the stabilizer level is lowered
to below 70 ppm, the problem can appear to be chronic.
Another potential stain-causer: potassium permanganate. If a
house’s water supply is high in iron, manganese or hydrogen
sulfide, many homeowners choose an iron/hydrogen sulfide reduction
filter for their water treatment system. This filter contains
manganese green sand, which reduces contaminants through an
oxidation/filtration process. Should green sand water mix with
make-up water, it can contribute to staining. The manganese in the
filter is expelled when the system recycles, and it will create a
pink/purple potassium permanganate stain when it comes in contact
with the pool finish.
Iron and scale are two common causes of staining in a pool, but
occasionally they work together to create a more obscure form of
discoloration. This hybrid stain, known as iron scale, can be
particularly difficult to remove, as standard treatment
doesn’t often work. The only way to alleviate this buildup of
layers is to remove first the top layer of scale, then treat the
iron stain that it previously covered.