Choosing The Right Liner For Your New Garden Pond
There are many different types of liners that can be used for your pond. Pre-formed plastic ones are sturdy, durable, and relatively easy to install but do not allow you to customize your pond. Concrete liners are extremely durable and permanent but can be very expensive, difficult to install, and should be left to professionals or serious do-it-your-selfers. The most common and versatile of all ponds liners are the synthetic polyethylene and butyl rubber liners.
These liners come in a variety of thicknesses and can accommodate virtually any shape you can come up with.
Polyethylene is one of the most common and affordable liner materials but lacks flexibility and tends to become brittle as it ages. It is much better suited for temporary setups. Butyl rubber, PVC, and LDPE (low density polyethylene) are more expensive but are much more durable and will last much longer. They come in a variety of sizes and thicknesses to suit your individual needs. It is a good idea to use an underlay pad under any lined pond to prevent punctures and leaks from developing. Do not cut corners here because if your liner should begin to leak, you will be required to tear your pond apart and start the process over. Commercial underlays are now readily available but in the past, sand, old carpet, felt, or even polyethylene bags have been used.
Sizing Your Liner
Because liner material is expensive and a liner that is too small will not do you any good, it is important to calculate the correct sized liner that you will need. To calculate the size follow these simple guidelines:
Measure the length of the pond at the longest point
Measure the width of the pond at the widest point
Measure the depth of the pond at its deepest point
Take twice the maximum depth and add it to the length at the longest point to get the overall length
Take twice the maximum depth and add it to the width at the widest point to get the overall width
Then add 12 to 24 inches to the overall length and overall width to provide enough overlap around the edges
An example would be if the pond is 10 feet long, 5 feet wide, and 2 feet deep; we would double the depth to 4 feet and add it to 10 feet, and then add 2 more feet for overlap to get a total length of 16 feet. To get the width we would double the depth to 4 feet and add it to the width of 5 feet, and then add 2 feet for overlap to get a width of 11 feet. We would end up needing a liner 16 by 11 feet.
Once the liner is sized, then we can then lay it in the pond opening, over the underlay and weigh it down with large smooth stones to help it form it's correct shape. Another option would be to slowly add water and allow the weight of the water to push the liner into shape while you make minor adjustments as necessary. You will want to secure any overlap with stones, rock, etc. Digging a pond can be a lot of work, but by taking your time and getting some help it can also be a lot of fun. Remember to take your time and do it right the first time because you won't be able to change it after the pond is filled. Buy the best liner you can afford and don't forget the underlay to protect the fragile lining. When this part is done then you can get on to the real fun of filling and aquascaping your new pond.