Makes sense, but when low, wouldn't the pressure push the polymer back out?
In a groundwater pond that is mostly sealed, when the pond water level declines, then the "pressure" in the adjacent groundwater aquifer also goes down - so it is not pushing back.
In a perfectly sealed pond where the water level declined due to evaporation, then the groundwater would tend to push back against the sealant.
However, the polymers are designed to be very resistive to pushing forces. When mixed, the precursor chemicals make a viscous liquid. However, when these chemicals interact and begin to set, they make very long-chain polymer molecules.
P.S. I believe the polymers will also dehydrate if the pond water level stays low for an extended period. For example, when the clay itself in the pond bottom is no longer moist. Dehydration will probably result in significant degradation.
P.P.S. I have worked with a different set of polymers at my job. If my general knowledge on the topic is incorrect as it applies to pond polymers, then someone please correct.
