The math says,
325,000 gallons per acre-foot. If your surface is one half acre, thats 162,500 gallons per foot of your water. 7000 gallons is (drumroll please) about one half inch of water in your pond. That is not much of a difference. Evaporation and transpiration will take more than that in a day I would guess. So to add one foot, you would need $1200 worth of tankers (23.2).
