Rebeck, 3GPM is a nice flow for a spring to drink out of and could start filling your pond. As the water level rises, and surface area expands, the rising water level will appear to stop, and or, evaporation rate can become equal to the inflow rate.
Consider how fast your water level would be rising at 3GPM in a bathtub....and how slow would it rise in a typical swimming pool, and would it rise at all in a football stadium....?
