Have them provide you with a list of references... then contact those folks and see how they like their ponds, and if any issues have arisen. I would like to go and see the contractor's work first-hand. Maybe some ponds that are 8-10 yrs old too, not just his newer work.

"Forget pounds and ounces, I'm figuring displacement!"

If we accept that: MBG(+)FGSF(=)HBG(F1)
And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1)
Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT?
PB answer: It depends.