Dave- thank you for your clarification. you are the only one that mentioned the question about super dry conditions of the clay. Some of it is crumbly to the touch. I will try the bentonite. The web site says they sell grades from a fine sand size particle to marble size pellets. What you would use marble size for I have no idea. The web site also says:
Years ago the NRCS or Soil Conservation Agents recommended using 1 to 3 pounds of sodium bentonite per square foot. Texas Sodium Bentonite, Inc. has been sealing ponds for over 14 years and after many years of field-testing a high quality sodium bentonite with various soils; we determined that this recommendation was not adequate to successfully seal most soils. These tests proved that the more porous soils did require more sodium bentonite clay to successfully treat.
Maybe this recommendation resulted in some of the dissatisfaction with SB as a pond sealant.
