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Ecodur 201: Trout Pond Coating Project (6 years later)


Fish farming is a major global business currently worth around $176 billion a year and expected to rise to nearly $220 billion by 2022. The biggest producer is China which produces 62% of the world’s farmed fish. Russia is seeing a surge in rainbow trout production with 98% of the that nation’s output coming out of the Leningrad region and that species has significant production in the US. This case study concerns a fish farm north of Phoenix in the vast Tonto National Forest in Arizona.

Castagra’s Ecodur was applied to this trout pond in 2012. Whilst there is an infinite number of variations in pond design, the core issues are common to all.



Fish pond water quality has variations among different species of fish that can be tolerated while still providing conditions that allow them to survive and thrive, however, trout, in general, are at the top end of the spectrum where they need the highest purity conditions and abundance of dissolved oxygen. In this particular case, the operator wanted his pond lined with a membrane that would not make any contribution in terms of toxicity and one that would be cost-effective and not require substantial repairs.

Prior to the Ecodur treatment six years ago, the pond had been losing water at the rate of 150 gallons a minute into the cracks and fissures in the rock substrate. With such a rough base, it was also important that the membrane not be punctured and would plug cracks. Exposed areas of the membrane to the sun needed also be highly resistant to Ultra Violet rays which can quickly degrade many conventional ones, causing leaks.


Ecodur was chosen six years ago because of its demonstrated performance in heavy industrial applications combined with its purity of zero VOCs, zero BPA, complete non-toxicity and neutrality in aquatic environments. 25-year brine tests, for instance, have shown no measurable deterioration and Ecodur has an ANSI/NSF-61 rating for use in contact with drinking water.

Ecodur is essentially a plasticised gypsum, made of renewable castor oil and recyclable gypsum. It has more than double the adhesion of most conventional epoxy coatings and plugs crack permanently. It has similar attributes when applied to concrete, brick and rebar. Importantly, it also retains its flexibility for the lifetime of the coating as it does too with retaining its ability to re-bond to original Ecodur coats should repairs be required. It can be applied in cold weather at or below freezing temperatures.

Application Results

The inspection of the drained pond revealed a minor defect of a few square inches in a very high-water flow rate area at the inlet that did not require a repair. Some minor ground movement was also found where the natural rock faulted with one part dropping about an inch, opening a small fissure. There had been no substantial water loss, peel-back or undercutting of the coating along the fault, so a repair was, again, deemed unnecessary.


Fish farm operator, Randy Slapnicka, drained and cleaned out tons of algae and fish muck in March, 2018, which was identical to what he did three years ago, the last time he did a major clean-out. He did not need to do any remedial coating work at the time nor did he feel a need to do any this time.

Prior to Ecodur, major work was needed each time and sometimes in between the three-year intervals. He has been operating the trout operation for about 20-years in this part of the Tonto National Forest. Mr. Slapnicka reported his complete satisfaction with Ecodur’s performance, meeting all his needs for cost-effectiveness and suitability for raising trout successfully.