xroads,

It is not possible to answer your water pumping question based on the available information.

The key factor is the permeability (ability to transmit fluids) of your sand bottom.

If you have very clean, coarse sand, and a very large "unbounded" water table aquifer, then you probably have very high permeability. In that case, it is possible that ten 2" trash pumps might not be capable of keeping your pond "bank full" during the periods when the water table subsides.

OTOH, if your sand contains some mixed in clay, or some clay layers in the depositional horizon, then you might have moderately low permeability. In that case, your pump might be able to keep up with your water leakage rate, and you can have a full pond at a reasonable cost.

I will say, that regardless of your actual permeability, the fluid flow rate is a linear function of the pressure difference. When you have to pump X gallons/day to keep your pond level 2' above the level of the water table, you will then have to pump 2X gallons/day to keep it 4' above the level of the water table.

My suggestion would be to test your required pumping rates BEFORE you finish the final shoreline of your pond. If it turns out to be too expensive to keep your pond full at the end of a six-month drought, then design the pond to be able to keep your fish alive during the "bad" times. Also design the pond to be a beautiful bank full pond, if you can cheaply keep it full when the water table is only down 1 foot. (That period at the start of the summer might be one of the busiest times of the year for you and family or friends at the pond.)

Good luck on your big project!