6 GPM = 8,640 G daily

Acre inch = 27,254 G

Daily loss [including evaporation] = .31" Excluding evaporation you could be .15-.2" daily loss due to seepage.

[In the pond rehab business we don't consider anything under .33" a reason to address in areas receiving at least 20" annual precipitation.]

Prior to rehab you were losing over 2" daily IIRC.

Your efforts reduced leak rate by 85-90%

Your reduction in water loss is reason for congratulations!

Per our multiple discussions your watershed and annual rainfall isn't sufficient to keep your pond full without assistance of supplemental irrigation. This serves as the impetus for your continued angst I guess. Obviously unless one of these factors is addressed [pond size reduction, increase watershed, supplemental irrigation] even a pond sealed like tupperware won't remain full due to atmospheric influence if precipitation cannot replace the loss. Pond was not designed appropriately.