How many gallons of water are in your 3+ acre pond?
I dug a 25'x25'x4' deep pond between yesterday and today, will treat the sandy soil with Soilfloc before I fill it with water, Not completely done, but done moving dirt. Small test pond. It would have gone faster if I had an excavator, but all I had was a FEL on the tractor. If the test works, I'll rent an excavator and put in some 1/20th - 1/10th acre ponds to raise some fish that aren't commonly easily found on the pond stocking market.
