Hi Ninja welcome to the forum. Feel free to reach out anytime on your pond project-I deal with pond building/rehab/repair all over the country and am happy to chat. If you're dealing with pure sand, you're correct no additive alone [bentonite or polymer] will seal it - must work with clay. Further, you're dealing with a water table pond which makes things even more challenging. My time is free to my Pond Boss forum family if you want to connect I can help outline some options and help you speculate budget. tj@hudlandmgmt.com

Many men go fishing all of their lives without knowing that it is not fish they are after. ~ Henry David Thoreau

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