Pond Boss Forums POND CONSTRUCTION Soil questions bentonite question

Bentonite is not toxic to fish at least when present in water at in normal concentrations. I think the guy loading it for your wife had his concepts confused. Bentonite can if poured near a specific spot where a relativel small leak is occurring will be absorbed into the leak area and swell to help slow or even stop a leak. Problem is if this area ever becomes dry (evaporation, drought) and the soil cracks the leak reforms. The success of this leak fixing method has lots of "it all depends" and I would not call it a reliable method.