Here's an update to the review I did earlier. I apologize to the manufacturer and seller. My leak was due to algae buildup on the waterfall coming from my bog filter. The algae got so high that water was actually leaking from a fold in the bog liner way in the back of the bog. I didn't notice where the water was leaking until I got to the point where I was removing the flat rocks that surround the filter. I ended up cleaning out the algae in the waterfall opening and put a half inch spacer under the liner around the filter. The spacer basically raised the level of the water inside the filter so there was a little more room for the waterfall to do it's job. Thankfully I got to that point prior to removing all the river rock in the pond bottom and the fish. Wow! Talk about a relief! But still, I think at this point, I would spend a little extra money at the beginning and still go for the thicker liner. Call it peace of mind but it's far better than tearing the whole thing apart and starting over.
Original review: This liner went in very easily and was just fine until a couple of weeks ago. The pond has been up and running for almost one year. It wintered very well for this past winter. The pond along with my bog filter contains about 250 gallons. All of a sudden, just a couple of weeks ago, I noticed I was losing about an inch and a half per day. At first I thought it might be evaporation because it is getting hotter in mid June. But I am losing water so fast it has to be a leak. I am in the process of removing everything in the pond....plants, river rock bottom, fish (5 Shubunkins), lights, everything. I will probably use it as additional underlayment for the new liner I am about to go out and buy at my local pond store. I will replace this 20 mil liner with a 45 mil. I thought because my pond wasn't all that big that I could get away with a thinner liner. I was wrong and it's now causing me a TON of work, not to mention the stress it will cause my fish! Do yourself a favor and buy a 45 mil EPDM liner. You will be much happier not having to replace it a year later!!
Liner was easy to install and trim with sharp scissors to meet dimensions. I used it to cover an unused hot tub. The koi fish are doing fine but I'm not crazy about the black look of the bottom of the pool. Will need to place rocks or something to take away the color of the liner. Hope it lasts the 15 years that it claims.