Pond Boss Forums INTRO Questions & Observations Bentonite Questions

I am no pond expert, by any means, however, bentonite I know about. Dry, powdered bentonite clay expands at approximately a 15 to one rate. I.E., if you put it down in an even 1/2" layer, and it's undisturbed, it will eventually (in a perfect world) be equivalent to about 6-8" thick. Sounds as though most till it into the top few inches of soil, so it actually is even thicker in the end.

The stuff is amazing. We've used it to seal off underground tank vaults to keep ground water from entering. Pour it down a well and it means a permanent seal that no groundwater or surface runoff will ever penetrate.

Doesn't really take that much, if it's an unbroken layer. Can't remember for sure, but a 50lb sack was along the lines of $8-10...by the ton, it's gotta be cheaper.