| [ZEK]This doesn't seem to be a problem with a few million swimming pools with plaster coatings? I would think this is would be a much easier & cheaper alternative to spray on polyurathane. There's also thousands of pool guys out there to work on plaster vs a few poly guys.[/quote]
Actually swimming pools crack and leak all the time and there is an entire industry built around the repair and replastering of swimming pools both concrete and fiberglass. That's why there are "thousands of guys out there to work on plaster". The difference is that a swimming pool is a relatively easy thing to repair, it just requires time and a check book.
A pond on the other hand is not a swimming pool but a live system that houses animals and shutting it down for a couple of months while the plaster is jackhammered off and reapplied, cracks filled or an alternative coating is applied is not an easy or inexpensive option. A large pond full of fish is at risk any time it's shut down or how about the risk to the fish load during long term quarantine or alternative housing. If the fish are of size long term quarantine can be a serious problem for a whole pond full of fish. It's a problem for a lot of people to just quarantine a couple of fish at a time now imagine the entire collection.
The reason the pond industry has looked for alternatives to a plaster pond are numerous but mostly for the security and integrity of the system and for the safety of the fish over the long haul. Polyurea when applied properly is actually cheaper in the long run over other coatings simply because it only needs to be applied once. All others to this date have a much shorter life expectancy and must be repaired or replaced over the lifetime of the pond.
Plaster can only be applied to a complete concrete shell but polyurea can be adapted to almost any type of structural system. This is also what makes EPDM liner so attractive for the short term.
Polyurea is being used in applications all over the world where other systems of water or non solvent based fluid containment systems have failed and yes polyurea can fail also but is almost always the fault of the installer or the lack of proper mechanical clamping so the leaks are at the penetrations and not through the poly itself. |