I think we already know your soils work best with soda ash. My thoughts are to measure filtration under different treatments. In particular, I would like to test cost equivalent application of soilfloc and bentonite to see how their filtration compares with sand as the filtration medium. Neither could perform better under field conditions and we could at least learn the best possible performance in sand one might expect from each. I also want to test the soda ash with our caliche underlain clay soils. I think they may respond well with this treatment where bentonite would not. I notice many of the ponds constructed near me noticeably filter water and are maintained by pumped water. So I think I will learn something that I can apply later when constructing a pond.
Another thing that interests me is how each might perform if the interface is punctured equivalently. Would they both filter away or would one or the other be less prone or perhaps have self healing properties?
To be sure there will be different prices depending on vendor. I just did a google search and that is the only site I visited. They recommended one unit per 3000 ft^2 and their cost was 557 (I think) when buying 15 units. Anyways, I will defer to 1320 lbs/acre at a cost of $5700/acre. Thank you for sharing this.