The liner is a major component in any pond whether it be a preformed shell, concrete, or rubber lining. I had read a great deal about EPDM liners and how to size them for the pond. I was most concerned about getting too small of a liner so I added 2-3 feet in all directions.
For the lower main pond 8x9xavg3 I purchased a 20×20 liner from a fellow off craigslist. The invoice showed it was an EPDM liner and the box was unopened. When I unrolled the liner I found out it was seamed in the middle. I was not able to find any negative reviews of professionally seamed liners. I saved about $75 off full retail for this liner and did not have to pay shipping or sales tax.
For the upper bog and falls I went to my local Pond supply store (Wakoola) and purchased a 10×15 liner which was far larger than I needed but allowed me some options for the bog design. I also purchased all the underlayment I would need for both sections of the pond. My estimates for the underlayment was a mere 20 square feet larger than I needed. I also purchased some sticky 2 sided seam tape at $5/foot to connect the bog liner and pond liner underneath where they overlapped.
The underlayment was cut to fit neatly inside all four sides and even the bottoms of my bog and main pond to help protect from rocks and roots. The main pond liner went in much easier than I thought but due to the rectangular shape I have several folds at the corners. I ran it up to the full height of the water falls knowing I would put heavy rocks on it. The upper bog liner was placed so that it overlayed the lower and acts as a second layer to the water line.
I filled the pond with water, smoothing and shaping the liner as it filled. About 1 foot from the top I cut in my bulkheads for jets and the skimmer. That is a very nerve racking step. Even more nerve racking was putting in a bulkhead near the skimmer for the bottom drain hose. I did not plan for that so I was working in tight quarters and drilling through wood with liner already stretched over it.
After about a week of tinkering and making sure nothing was leaking I began trimming and burying the liner on the outside of the frames. Once my pump was running and waterfall rocks placed I found that my bog would overflow on the backside when running the pump at high speed. So I built it up with 2×2’s and overlayed the bog liner again. Good thing I left a good bit of extra around the edges.
