Replace a Pool Liner

Technical Support to replace a pool liner

CGT Features and Benefits


CGT liner material has been manufactured since 1968 – longer than any other pool liner manufacturer in the world. 100% Manufactured in Canada


Formulated to have anti-bacterial/anti-fungal properties to resist foreign microbial growth and contain a protective top coat to preserve the printed patterns.


Ultimate UV protection from the sun to maintain a vibrant color & appearance longer than any other vinyl liner.


Our liner patterns are the best-selling and award-winning pieces on the market.


Superior chlorine resistance, reducing vinyl fade with proper pool maintenance and care.


Manufactured in accordance with ISO 14001 and ISO 9001 certifications, measuring quality and promising performance.

Looking to Replace a Pool Liner | Vinyl Quality Highlights

Looking to replace a pool liner, it’s important to know that all CGT pool liner compounds are prepared using the highest quality raw materials available on the world market. Raw material selection and product enhancement is directed through our on-going research and development program, focusing on key property requirements of vinyl pool liners.

Quality of CGT Vinyl

  • High resistance to breaking, tearing and puncturing.
  • Excellent resistance to cracking at low temperatures (-29°C / -20°F).
  • Low rate of plasticizer loss resulting in a slow rate of stiffening.
  • Resistance to degradation from UV radiation.
  • Resistance of the plain pool lining material to chlorine bleaching is good, printed pool liners are formulated to provide excellent resistance to color loss from chlorine exposure.
  • Anti-microbial additives within the formulation provides additional protection to regular chlorination and algaecide treatment.
  • Special clear top coat applied over print patterns is formulated to maximize protection of the print against abrasion and reduce the adhesion of soil to the liner.

If you Replace a Pool Liner | Advantages of Vinyl Pool Liners

Before you replace a pool liner, it’s important to understand that vinyl liner swimming pools have been constructed in North America for well over 50 years, and just like any other industry the technology and materials used to construct the pool are always advancing.

Here is why consumers choose vinyl over other materials:

  • Vinyl liner swimming pool structures are assembled in modular panels, the structure has unlimited shape and size potential. This allows fabricators to gel into tight access areas.
  • Today’s vinyl liners are available in different thicknesses and UV protection is better than ever. We find the vinyl liner to be very durable. Should the liner become damaged it can be easily patched with original material for an invisible repair without draining the pool water.
  • The shipping advantage of a vinyl swimming pool is substantial and will contribute to lower initial cost.
  • Vinyl liner construction and labour is very cost efficient.
  • Vinyl liners are versatile in pattern and style choice, ability to customize to exterior style, and can be replaced easily and as frequent as the homeowner alters the look of their exterior space and style.
  • Vinyl liners come in infinite customizable patterns. Print patterns have been significantly enhanced by the application of electronically engraved printing cylinder technology. This technology produces patterns that are crisp and well defined to enhance your pool.
  • Vinyl swimming pools are resilient to freeze/thaw cycles found in seasonal climates.
  • CGT vinyl liner material meets or exceeds the CFFA Performance Standard for Vinyl Inground Swimming Pool Liners.

When you Replace a Pool Liner | Avoid Over-Stretching Vinyl Pool Liners

Learn before you replace a pool liner, as there are many references in technical literature concerning the adverse effects of excessive mechanical stress on the weather resistance properties for various types of polymers.

Although vinyl liners are designed with an ultimate elongation over 300%, they are still vulnerable to this phenomenon. There is general awareness in the industry that excess stretch in an installed liner can result in premature failure and liner fabricators have been successful in reducing the built-in stress of their liners to a minimum. Curvatures of corners have been increased and computer technology has enabled more accurate measuring and design of liner dimensions for pools of all shapes and sizes.

This phenomena is most often seen at the area below the beading where gauge reduction occurs close to the anchor point of the liner and in corners of the pool that receive the greatest heat exposure from the sun.

Vinyl Stretch 1
Vinyl Stretch 2

When you replace a pool liner, the result of gauge variation and damage caused by over-stretching vinyl.

To prevent overstretching make sure your pool is accurately measured by a pool professional when considering replacement of a vinyl liner.

Vinyl Measuring

Avoid over-stretching a vinyl liner.

Chlorine Levels

Chlorine Balance | After you replace a pool liner

Keeping your water chemistry balanced – especially your free chlorine level – is the key to maintaining the appearance of your liner for a long lime. Chlorine affects your pool water’s pH and alkalinity levels. If your pool water is often acidic (pH less than 7) or the free chlorine level is maintained above 3.0 ppm, it can degrade your liner more quickly. It is always good practice to add chemicals into your pool by diluting it in water before the addition. Recommended values of pH and free chlorine are 7.2 – 7.6 and 1.0 – 3.0 ppm, respectively.

CGT formulates our vinyl and inks to provide superior chlorine (bleach) resistance and a low rate of plasticizer loss to minimize the rate of liner degradation. Exposure of the vinyl liner material to the water chemistry parameters outside of the recommended ranges can result in a variety of negative effects. Some of these include liner wrinkling, liner color loss/staining and stiffening of the liner material which can lead to premature tearing and failure of the liner to hold water. All of these result in a shortened service life for the liner.

RECOMMENDED – pH levels: 7.2 – 7.6

RECOMMEND – Free Chlorine: 1.0 – 3.0 ppm


CGT formulates our vinyl and inks to provide superior chlorine (bleach) resistance and low rate of plasticizer loss to minimize the rate of all liner degradation.

Automatic Pool Covers

Automatic pool covers serve to help reduce operating costs by retaining heat in the pool water, and minimizing water loss due to evaporation, chemical use and debris from getting into the pool with just one push of a button. The interlocking slat cover keeps out large amounts of debris, but the tight fitting nature of automatic pool covers can allow for a buildup of heat and chlorine in the head space above the pool water and below the underside of the cover. With this in mind, it is important that automatic covers and vented or periodically opened to minimize the heat buildup and increased free chlorine conditions to preserve your vinyl liner reduce the chances of wrinkling and discolouration.

Salt Water Chlorine Generators

The use of salt water chlorine generators to supply free chlorine to pool water for sanitization has increased significantly in recent years. Many homeowners who have been sold salt water chlorine generators do not realize that their system is indeed a chlorine generator and not simply the use of salt to sanitize their pool. Although these units provide more consistent dosing of chlorine to pool water than manual dosing, there are several factors to consider so that their use does not lead to abuse and cause exposure of the liner material to excessive levels of free chlorine. The first thing to remember with the use of these systems is that the requirement for diligence in testing and balancing pool water to maintain parameters within the recommended ranges is as important as it is with manual chemical additions.


Before using a salt water chlorine generator, ensure that your pool system is properly set up by a pool professional. Some homeowners install chlorine generators with the belief they are ‘set it and forget it’ equipment, which in fact is not true.

There are many chlorination products on the market, and they all have unique chlorination and pH levels.


Typical pool staining results from micro-organism growth, precipitation of oxidized metallic compounds or organic contaminants. CGT vinyl liners are formulated to have anti-bacterial/anti-fungal properties to resist foreign microbial growth and contain a protective top coal to preserve the printed patterns.

The most common types of staining seen are:

Black Algae Staining

These are small block spots on the pool surface from chlorine resistant organisms that require physical contact (with a nylon brush) in addition to chlorine to remove. Further steps in addition to the physical removal are to: reduce pH to lower limit (7.2), superchlorinate the water (10.0 ppm), and add a dose of a quaternary type algaecide. These can all aid in removal of the black spots.

Black and Pink Staining

These pink or grey blotches which can be seen on the liner are the result of the metabolic process of micro-organisms. A dye is excreted that is highly soluble in plasticizers used in flexible PVC and has the potential to migrate through the entire thickness of the liner from its origin on the back side. This staining can be seen on both sides of the liner and generally requires liner replacement and chlorination of the contaminated surfaces to correct.

Metal Staining

Copper, Iron and Manganese will form oxides in chlorinated pool water and can deposit on the pool surface. These stains are generally black, brown or grey in colour. The metals may be introduced into the pool via the water source used to fill the pool.


Pool Goo and Organic Contaminants

The consensus in the pool industry is that there are several sources of sticky substances, often referred to as “pool goo” or “pool tar” that adhere and coat portions of the pool surface.

Source of Issue:

  1. Compounds formed from the interaction of ammonium compounds in some algaecides and decaying organic material such as leaves, grass, insects etc.
  2. Interaction of algaecides with other substances. Even chlorine can interact with algaecide and form sticky material if both chlorine and algaecide exceed the recommended dosage levels.
  3. Chlorine goo can form when organic material from cosmetics, tanning lotions, etc. are oxidized by high chlorine concentrations resulting in a beige, waxy material.
  4. A light coating of vinyl plasticizer may exude to the surface of newly-installed liners during the first idle period of winterization. This material is clear and only turns dark if contaminated with dirt. The occurrence of pool goo is only known to occur with the first winterization of the liner.
  5. Pool scum is a ring that forms around the pool at the water line and is made of soil contaminants from suntan lotion, environmental pollution, and organic materials from bather load etc.

Potential Ways for Eliminating Pool Goo

  1. Reduce and maintain pH at 7.0 – 7.2.
  2. Super chlorinate to 6.0 – 8.0 ppm and let equilibrate to free chlorine concentration of 1.0 – 3.0 ppm.
  3. Slop using algaecides.
  4. Use heater to speed up warming of water (if available).
  5. Continue to circulate water and monitor pressure of filter.
  6. Backwash filter as often as required.


Although rare with vinyl liners, cracking can occur in two different forms: pressure cracking and cold cracking.

Cold Cracking

Incidents of installed liner failures due to cold crack are extremely rare since the liner is held in place by the beading and water preventing significant flex.

CGT’s in-ground swimming pool vinyl has been formulated to meet a cold crack rating of -29°C (-20°F) according to industry test method ASTM D1790.

Damage from ice causes ruptures due to high pressure and is not the result of low temperature flex failure.


CGT’s Cold Crack Rating according to test method ASTM DI790 -29°C (-20°F).

Pressure Cracking

When handling material in a warehouse, folding of fabricated liners can cause pressure cracks. This can develop from o crease of a double or triple fold and environments like: high temperature during storage, higher pressures from weight of material, and duration of time it is left folded – all have an impact on pressure crocks. Once folded and stored in a warehouse, fabricated liners can be at increased risk for cracking with the following three conditions:


Recommendations for Minimizing Formation of Cracks

  1. Do not unfold liners at temperatures below 20°C (68°F), in the plant or prior to installation of the liner at the pool site. This is especially critical during installation in the fall, when morning as well as day lime temperature can be well below 20°C (68°F). DO NOT unfold liners of temperatures below 20°C (68° F)
  2. Do not store a boxed liner outside or in an unheated storage area prior to installation at the pool site especially during the cooler spring or pool season. The liner may not worm up evenly in a span of a few hours in the morning. DO NOT store boxed liner in environment below 20°C (68° F) prior to installation
  3. Minimize the length of time finished liners are stored in cartons.
  4. Ideal storage temperature is 20-22°C (68-72°F).
  5. Allow the liner to climate to room temperature before handling.
  6. Minimize or eliminate stacking of liner cartons to reduce pressure. Ideal liner storage temperature 20 – 22°C (68 – 72°F)
  7. Keep the number of folds in the liner to a minimum.
  8. Use larger cartons for large liners; cartons that resist collapsing under pressure will afford more protection to the liner.


Research by both chemical suppliers and vinyl manufacturers have confirmed that wrinkles in swimming pool liners develop due to the growth of the vinyl through water absorption. Technical articles published in the past hove stressed the adverse affect of low pH as the main cause of liner growth. However, further research has shown that prolonged exposure to high levels of sanitizer (chlorine) results in excessive water absorption. In fact, controlling sanitizer levels is the number one priority when maintaining proper water chemistry to avoid wrinkling issues.

A number of incidents of wrinkling have been reported from commercial or semi-commercial installations which are, more often than not, indoor pools. These pools carry a high bather load and as a result operators apply chlorine or bromine sanitizers at high levels as insurance against sanitation problems in response to health deportment requirements. Severe colour loss (bleaching) of the liner is evident in these occurrences confirming exposure to high sanitizer concentration over long periods.

The root cause of wrinkle development has proven to be excessive chlorine or bromine levels, causing ongoing absorption of water and dimensional growth of liners.

Wrinkling 1
Wrinkling 2

Reducing the Potential of Liner Wrinkling

The most effective method of reducing the potential for vinyl liner wrinkling is through the maintenance of proper water chemistry. Keeping the free chlorine concentration within the recommended limits of 1.0 – 3.0 ppm, keeping pH within the limits of 7.2 – 7.6 and maintaining cyanuric acid stabilizer levels within the 25 – 50 ppm range will collectively reduce the potential for water absorption leading to liner wrinkling.

It is important to understand that the various methods of chlorination have different impacts on pH. Salt water chlorine generators tend to cause pH to rise as do sodium and calcium hypochlorite. Use of Trichlor (Trichloroisocyanuric acid) will reduce the pH of the pool water causing a more corrosive environment and Dichloroisocyanurate (Dichlor granules) are very slightly acidic, but the closest to a neutral pH. Keep in mind that both Trichlor and Dichlor contain cyanuric acid stabilizer reducing or eliminating the need for separate stabilizer additions.

RECOMMENDED – pH levels 7.2 – 7.6

RECOMMENDED – Free Chlorine 1.0 – 3.0 ppm

RECOMMENDED – Cyanuric acid stabilizer level 25-50 ppm

Vinyl Care & Maintenance

With a strong, resilient CGT vinyl pool liner, you have ensured that your pool liner remains the focal point of your pool. We have designed and manufactured our CGT vinyl to help your pool liner survive the extremes of nature, sun, heat, chemicals and the harshest conditions of winter.

Liner Care and Maintenance

Our specially formulated vinyl gives extended protection against biological growth and pattern loss. However, maintaining the chemistry of your pool water at recommended levels is essential to prolonged liner life as most liner problems are due to a misuse of chemicals, either too much or too little. For the proper chemical balance, your dealer can provide you with the test kits to measure the chemicals in your pool water. CGT recommends maintaining pool water chemistry at the following levels to maximize the life of your vinyl liner.

  1. Check Total Alkalinity
    Your water test kit or your dealer’s test will show a total alkalinity reading. Simply put, it’s the ability of your pool water to counteract changes in the pH level.
    Recommended—Total alkalinity level: 80-120 ppm
  2. Check pH
    pH is the measure of acidity/basicity level in your pool. A proper pH level (7.2 to 7.6) not only increases human comfort, but also helps chlorine clean your pool better, because chlorine needs a certain pH level to kill bacteria and algae effectively.
    Recommended— pH: 7.2 -7.6
  3. Check Free Chlorine
    Your water test kit or your dealer’s test will show a total free chlorine reading, which is the concentration of residual chlorine in water present as dissolved gas, hypochlorous acid, and/or hypchlorite ion.
    Recommended— Free Chlorine Level: 1.0 – 3.0 ppm
  4. Check Chlorine Stabilizer
    All outdoor vinyl pools should be routinely stabilized with cyanuric acid in a range between 25 ppm and 50 ppm. The use of stabilizer helps to maintain the free chlorine levels in an outdoor pool.
    Recommended— Chlorine Stabilizer: 25 – 50 ppm

RECOMMENDED – Total alkalinity level: 80-120 ppm

RECOMMENDED – 1pH: 7.2 -7.6

RECOMMENDED – Free Chlorine Level: 1.0 – 3.0 ppm

RECOMMENDED – Chlorine Stabilizer: 25 – 50 ppm

Other Safety Checks

Use the recommended personal protective equipment (PPE) when handling any chemicals as per the chemical manufacturer’s directions. Only add one chemical of a time and allow each chemical to circulate throughout the pool before adding a second chemical. Remember to always pre-dilute your chemicals with water before addition to the pool. Certain combinations of chemicals at a high concentration can cause bleaching of the pool surface.

Test for the presence of dissolved metals because they may directly stain the vinyl liner or combine with calcium hardness to form discolored deposits.

Each CGT vinyl pool liner has a special transparent topcoat that protects the print pattern from abrasion and soil adhesion. To maintain its effectiveness, avoid using abrasive cleaning agents or cleaning aids.

Closing the pool

At the end of the pool season:

  • Test pool water.
  • Never close a pool without circulating the pool water for several hours after the final additions of chemicals (chlorine may settle in the deep end and bleach the liner).
  • Clean and vacuum the pool from top to bottom.
  • Adjust the water for winterization.


Use a proper fitting winter pool cover, tightly sealed around the perimeter of the pool. It will prevent the accumulation of debris such as leaves and insects during the off season. Should you have any questions about your pool, call your dealer – they are your pool professionals.

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