We all have heard the childhood legend of Hans Brinker, the story of the brave Dutch boy who supposedly put his finger in the dyke to prevent a flood. Unlike Hans, who recognized the dangers of a small leak and spent a cold frightful night with one hand holding back the water, I ignored a small green puddle that appeared on the outside wall of my koi pond "Varsity". I watched it cautiously day after day, knowing that very soon I would have to fix the persistent leak. Finally after several months, I was noticing the green puddle enlarge and the pond level receding a few inches (1 inch = 2.54 centimeters) each day. If I was away from the pond for a few days, I could not trust the pond's integrity. I knew the time had come and I had to fix the leak! 

This 4500-gallon (17000-liter) koi pond started as a reflection pond for small koi. In later years, it was remodeled several times to make the pond deeper and more suitable for larger koi. Although the vertical and horizontal joints of the remodel had been filled and reinforced, they continued to be the weak spots of the construction and a constant problem. In 1999, the entire pond had been re-surfaced with plaster due to yet another leak. I was told that the repair was not forever and that eventually I would be facing the same problem. Eight years later, to be precise, 2007, my pond had another major leak, in the same area.

I had a few options. The least expensive was to refill the crack with a waterproof bonding material. There were no guarantees and the process had a doubtful reliability. The one advantage was that the patch could be made underwater and the fish could remain in the pond. The crew was not sure if the procedure would work, nor for how long! Living in southern California, earth movement is a constant threat to concrete ponds. An alternative option was to use a PVC liner, but I didn't want the unsightly folds and crevices, places for bacteria to hide.

The most reliable solution was to coat the entire pond with a relatively new substance called polyurea. All the people I called on for advice said the same thing -- polyurea was my best solution. Because I had heard so many wonderful comments about this new way to surface koi ponds, I attended a seminar session to hear the whole story.

The presenter was Tim Zuber, the foremost authority in polyurea containment construction. An energitic presenter, Tim described the benefits of polyurea elastomer spray as a veritable "wonder" substance! This industrial plastic is used in automotive, industrial, marine, commercial and military applications. It is waterproof, inert, indestructible, and immediately ready.

Its strength and elasticity is truly amazing. Part of Tim's presentation was a video illustrating the incredible traits of this substance. Neither tons of falling earth nor a multi-ton boulder would rupture the liner. When a wall of dirt caved in underneath the liner, the polyurea stretched but did not tear. Because of these wonderful characteristics, Tim adapted the process of polyurea to the pond and water garden industry knowing it would revolutionize the way ponds are constructed and repaired. And so it has!

The material, black in color, is sprayed on to the floor and walls of the pond, drying almost immediately. Being sprayed, it takes the form of the pond with neither folds nor seams. Polyurea can be sprayed to any thickness. However, because of its innate strength, it does not need to be applied in a thick layer. The non-toxic substance is not harmed by some of the chemicals used in koi husbandry such as potassium permanganate and salt. Other characteristics of this substance include flexiblility, unaffected by extreme temperatures, and holding up well to UV exposure. I was told if I wanted to add an extension to the pond later, it would be a simple remodel. It is easy to patch or join with new extensions of the same material.

The formula is sprayed carefully around fittings such as bulkheads and drains to ensure a tight seal. Amazingly, it needs no cure time. The lining can be rinsed with a hose and the pond filled and stocked the next day! I was convinced this was the way to go.

William Lim, the designer and manufacturer of the Wave pumps and other pond equipment introduced me to Paul Parszik, owner of Artisan Aquatics in Torrance California. Tim Zuber trained Paul in the specialized techniques of spraying polyurea for koi ponds and water garden features. I was very impressed with Paul's presentation and his approach to my project.

A few weeks prior to the big day, I moved all my koi to another filtered koi pond for safekeeping. I emptied the leaky pond and allowed it to dry thoroughly. The surface must be totally dry before applying the polyurea.

Paul meticulously prepared the pond site, taking care to cover and protect areas not to be sprayed. His truck, equipped with canisters of polyurea, and the transport system with hoses and valves, was as pristine as a hospital operating room. The care Paul took to construct his specialized truck reflects the same care he takes with his projects. A former engineer and test pilot, he knows that attention to detail is extremely important.

Paul explained that polyurea is composed of two substances combined at the last minute in the nozzle as it is sprayed. The actual application took only a few hours. Each section was scrutinized closely to make sure the coverage was even and adequate.

The next day, Paul replaced the dozen air stones that surrounded the perimeter of the pond. He also suggested installing an air dome to the bottom drain, a great suggestion. All of Paul's work was accomplished effortlessly and perfectly. I then filled the pond and re-started the pumps. Even though the filtration system had been off a few weeks, the pond never went through the green water stage. The bacteria in the filter had stayed alive. The next week, I introduced the koi to their remodeled home. They love it!

I am convinced I made the correct choice in selecting polyurea for my koi pond. I no longer worry about the leaks in the pond caused by earth movement. The bottom and sides are sleek black and there are signs of the good short algae growth.