Choosing Among Fish Pond Liners

When choosing among the various fish pond liners available, there are a number of considerations and choices to make. If you're just starting out, the many choices may seem daunting. Should you use a preformed pond, or a flexible liner? What type of material is best? How deep is deep enough for fish? This page will attempt to run through a few of the more common questions related to choosing the right fish pond liner for your particular project.

goldfish pond liners
A pond goldfish.

What kind of fish?

The first question to ask is what kind of fish do you plan on housing in your pond? Goldfish are less demanding than koi, and will naturally require less in terms depth, feeding schedules and filtration requirements. With regards to choosing a liner, it is definitely possible to go with a rigid preformed pond if housing goldfish, especially some of the smaller fancy varieties. However, if you do decide to go with a preformed pond, try to get the deepest one you can since the deeper the water, the easier it is to regulate for temperature and chemical balance. If you plan on housing koi in your pond, or plan to upgrade to koi in the future, it would be our recommendation to forget about preformed ponds and use a proper koi pond liner (discussed further below).


Our Liner Recommendations

Materials Available

The most common materials used as koi pond liners are flexible in nature due to the speed and ease of installation. These liners are typically made out of rubber (either EPDM or BUTYL), or a flexible plastic (polyethylene or polypropylene). For a detailed rundown of these various options, please see our page on Choosing a Pond Liner, or our page on BUTYL vs. EPDM. Whatever material you decide to go with as a fish pond liner, be sure to choose a liner that is safe for fish; meaning that the liner does not leach harmful chemicals into the water. All of the liners we sell here at are safe for fish.


EPDM rubber liners are a popular option for small to medium sized ponds where liner flexiblity is important, such as if the pond has many shelves, or corners that the liner must bend around. One example of a popular EPDM liner is Firestone's PondGuard. Reinforced polyethylene liners (RPE) are also becoming quite popular, the advantage being they are much lighter, stronger and more puncture resistant than EPDM. The downside of RPE is that it is stiffer to work with, making it ideal for ponds or lakes that don't have many shelves or tight corners which require high flexibility.

Whatever liner you decide on, an important feature to watch out for is UV resistance. If a liner is not UV resistant and is exposed to sunlight (even through water), the liner will loose it's flexibility and begin to break down quite quickly. Most quality liners out there (including all the liner options we carry) are UV resistant, but some cheaper options out there aren't; so be sure to check before you purchase. Even if a liner is UV resistant, it's always a good idea to cover the liner above water level. This will help keep the liner in good shape for years to come.

Proper Depth

For a Koi pond it's best to have an area of the pond that is at least 4 feet deep. If you can make it even deeper, then great. The deeper the water in a pond (and the more volume), the less prone the pond is to rapid temperature fluctuations. As well, when the sun comes out, it can heat up the top layer of the water quite quickly. Having a nice deep pond allows the fish to retreat to cooler waters below on a hot day. One of the most common problems with using precast/preformed ponds as fish pond liners is the lack of depth in most cases. Of course, this isn't the case for all precast ponds. However, even if you do find a nice deep precast fiberglass liner, often times these liners are difficult to ship and can be quite costly. The easier way to build a pond that has more than enough depth is to use a flexible liner; either EPDM, BUTYL or PVC.

To learn more about fish in general, please see our page on Koi Fish Information, Koi Ponds, or Goldfish Ponds. For other pond topics, please see the table of contents at the bottom of our home page, or the navigation bar on the left. Thanks for visiting!

Click Here to Return from Fish Pond Liners to Pond Liners

Click Here to Return from Fish Pond Liners to our Home Page