We know that the primary job of pond liners is to hold the water in your pond.
Pond liners can be custom manufactured for individual ponds in-factory or purchased as pre-cut sheets which can be joined together using methods like welding or taping. The weight, thickness and pliability of the material will all influence what you can achieve and how difficult it will be to install.
It’s important to make sure that the pond liner you choose to install ticks a few boxes.
- The pond liner should be able to remain stable in fluctuating temperatures.
- If your pond level drops, an exposed liner should be able to stand up to both UV rays and harsh weather conditions.
- The pond liner should be chemical resistant.
- If your pond is stocked with fish, be sure to check the toxicity rating of the liner you’re considering.
- The liner material you choose should be flexible enough to conform and mould to the contours of your pond but not stretch to the point of deformity.
Comparing the Top 3 Pond Liner Materials
Because not all pond liners are created equal, it pays to know the difference between pond liner materials before you make the investment.
High-Density Polyethylene – HDPE
PROS: Cost-effective HDPE plastic is durable, with a lifespan of up to 36 years when covered. It has very good UV resistance and functions well in cold temperatures. The material is very stiff and strong, so less prone to sudden length-wise tears. Its most desirable property is its superior resistance to a wide range of chemicals. HDPE is fish-friendly, so well suited for fishponds. All of this, coupled with the fact that multiple sheets can be “welded” together, makes HDPE one of the most popular geomembrane pond liners worldwide.
CONS: The downside of HDPE is that the weight and rigidity of the material make it expensive to ship. Additionally, the material cannot be custom shaped in a factory. Installations costs can mount up as HDPE pond liners require professional installation. HDPE can expand at high temperatures and become loose. The material is also vulnerable to punctures and surface scratches and is known to develop stress cracks over time.
Low-Density Polyethylene – LLDPE
LLDPE AND HDPE are made from the same plastic and thus have several properties in common.
PROS: LLDPE is inexpensive, functions well in fluctuating temperatures and is non-toxic to fish. LLDPE liners are most commonly used to contain water contaminated with waste or hazardous chemicals. LLDPE is less dense and much softer than HDPE which makes it more pliable and flexible. Installation is easier as it can be better moulded around tight corners and into nooks and crannies with fewer wrinkles. LLDPE is less prone to stress cracks.
CONS: LLDPE materials cannot be custom-fabricated and must be professionally installed in sheets welded together. LLDPE liners have less tensile strength and are more susceptible to length-wise tears and deformation in high temperatures. This material is not quite as resistant to UV rays, oxidation and chemicals as HDPE so may not be as durable or long-lasting when exposed to the elements.
Flexible Polypropylene – fPP
PROS: If your priority is a UV and chemical-resistant, fish-safe liner with physical strength, plasticity and flexibility then fPP is a material to consider. This liner is heat treatable, can be seamed through welding and is easily moulded, and form-fitted to a pond’s tightest corners, recesses and even irregular surfaces. fPP geomembranes have good gripping power on pond slopes and rough terrain.
These moderately priced pond liners are quite resistant to tears, punctures and scratches and can take a lot of strain and stretch from many angles without breaking or deforming. The material remains pliable up to -50°C which makes fPP a top choice for ponds subjected to harsh temperature changes. fPP liners can also be custom-fabricated in large pieces and folded up in the factory, which is advantageous for lining a uniquely shaped pond. When covered, an fPP pond liner can have a lifespan of up to 30 years.
CONS: Although resistant to many chemicals, fPP is vulnerable to hydrocarbons which include benzene, chlorine-containing chemicals, oils, animal fats and strong oxidants. Exposure to these chemicals can cause stress cracks, particularly along folds and wrinkles.
When installing your chosen pond liner, it’s imperative to make sure that ground irregularities or objects underneath the pond liner don’t cause it to snag, puncture or tear.
The Pool Spa team knows their stuff. Chat to one of their friendly experts today about which pond liners would best suit your application. Also, check out their range of pond pumps to assist in keeping your pond in optimum condition.