While liners are the exception rather than the rule on the West Coast, service technicians in other locations are much more likely to be familiar with the special care that liners require.

Even the highest quality liner is still subject to staining, wrinkling, shrinking, stretching, or discoloration if the proper water balance is not maintained, if debris is allowed to remain in the water, or if water treatment chemicals are used improperly.

Here, we take a look at some of the problems that can affect vinyl liners and the steps you can take to mitigate them.

Staining

The addition of a single chemical can damage a pool liner if it is not allowed to circulate sufficiently. If chemicals settle in the deep end, they can stain the liner. Spot bleaching of vinyl liners can occur if undissolved particles of calcium hypochlorite or other slow-dissolving sanitizers are allowed to rest in any one location. This can be prevented by pre-dissolving sanitizers in a bucket and adding the solution to the water by pouring it through a sieve.

Using large, single doses of muriatic acid to adjust pH or alkalinity levels can also damage vinyl liners. When it is not sufficiently blended with pool water, the acid will chemically attack the liner’s pattern. Any chemical added to pool water should be allowed to circulate throughout the water prior to adding another chemical, because certain combinations of pool chemicals at high concentrations can bleach the liners.

When the pool is closed for the season, a winter cover that tightly seals around the perimeter should be used to prevent the accumulation of organic debris such as nuts, leaves, and insects over the fall and winter months. Organic debris allowed to remain on vinyl surfaces can cause unsightly staining that can require months of regular chlorine use to remove. And – under certain conditions, fungi can grow on this debris, producing a pink stain on the vinyl.

Pink stains or pink-colored blotches on vinyl pool liners are caused by a pink pigment excreted by bacterial microorganisms such as streptoverticillium reticulum. These microbes are metabolic products of various fungi and bacteria that can be affected by light, temperature, oxygen, and pH.

This pink dye can easily migrate throughout the thickness of the liner.

While the surface dye is easily bleached by chlorine, new dye will simply migrate to replace it, making it seem like the chlorine is having no effect on the stain.

Furthermore, pink staining may also occur on the underside of the vinyl liner. The growth may take place on the soil or backing materials like foam, felt, or tape. And even though an antimicrobial agent is used in the vinyl formulation, the dye can migrate from unprotected areas, causing staining.

If the liner is replaced, it is essential to remove all contaminated areas, and the entire pool shell (floor and walls) must be disinfected with a liquid chlorine spray or some other suitable disinfectant.

Liners installed in areas with a high water table, where the liner is always in contact with water contaminated with microorganisms, are susceptible to pink staining.

Using disinfectants at these sites may be ineffective because they are quickly washed away. One solution is to use a barrier like a plastic sheet or layer of polyethylene between the shell and the liner.

Bleaching

Vinyl liner colors such as white, turquoise, light blue, gray, and royal blue have excellent resistance to chlorine bleaching. Vinyl liners of medium

Vinyl liner pool by Latham Pools. https://www.lathampool.com/vinyl-liner-pools Vinyl

From page 14

blue, however, are susceptible to loss of color if they are exposed to high trichlor concentrations for a period as short as 6 hours. The reasons are a high available chlorine content of 90 percent, low solubility of the granules or puck, and the extremely low pH produced at the contact site.

Dichlor, calcium hypochlorite, and sodium hypochlorite (liquid chlorine) do not have as immediate or severe effect as long as they are not mixed with other chemicals during or short- ly after they are added to the pool.

Solutions of these types of chlorine can be applied directly to the liner for a few hours to bleach out stains without adversely affecting the liner.

Take care to monitor the concentration of chlorine used for superchlorination or shocking, or else gradual bleaching of most blue liners will occur.

Pool Tar

Sticky substances known as “pool tar” can adhere and coat vinyl pool liners.

This is sometimes caused by the in- teraction of the quaternary ammonium compounds used in algicides with decaying leaves, grass, and insects.

A sticky material can also result from the interaction of chlorine with algicides. On pools using automatic chlorinators, the interaction of quatbased algicides with chlorine can result in a gummy material that is fed into the pool, gradually adhering to the liner.

Also, a beige, waxy substance can result through the oxidation of certain tanning lotions and cosmetics by high chlorine levels.

Sometimes, a light coating of vinyl plasticizer material, which turns darker when contaminated with dirt, can rise to the surface of newly installed liners during their first winterization. This is generally attributed to lack of circulation.

When the pool is re-opened for the season, allowed to warm up to about 70 degrees, chlorinated and circulated for about two weeks, it usually disappears.

Wrinkling and Stretching

Even in a properly sized vinyl liner, wrinkles can develop as the liner absorbs water, stretching it. The cause of excessive water absorption is usually attributed to high levels of chlorine.

It is essential to control water chemistry to maintain the integrity of pool liners, because if sanitizers are allowed to remain high, as much as five times the normal amount of water can be absorbed.

Manufacturers have conducted immersion testing using chlorinated and brominated water in the 20-50 ppm range that has shown that liners continue to gain weight indefinitely, causing the liner to increase in size by as much as 3 percent.

Chlorine levels should not be allowed to remain higher than 3 ppm for an extended period of time to avoid stretching and wrinkling. Wrinkling caused by overusing chlorine or bromine to treat cloudy water introduced by bathers can be avoided by using a clarifier to coagulate particulates so they can be removed by filtration.

It is also important to control pH levels to prevent wrinkling.

A low pH of 7, for example, can cause a vinyl liner to discolor, wrinkle, stretch, lose strength, and increase in weight.

Meanwhile, a high pH of above 7.6 causes vinyl to wrinkle, shrink, lose

weight, and expand. -o*'1’ © 7