Harvey,
Two thoughts.
How much land do you want to irrigate? And, what's the maximum amount of water you need to maintain your pond level? Figure out those numbers, then calculate the amount of water you need to accomplish those tasks. Then, you can tell your well driller your needs, and he can advise you about pump size, etc.
To calculate water volume, remember this..one acre one inch deep is 27,000 gallons. So, if you want to irrigate a lawn one inch every third day, and you want to maintain a one acre pond against evaporation loss in the summer, you can calculate water needs.
Second, if you want to add oxygen to well water, break up your well water before it flows into the pond. Some people run it over rocks, others flow across corrugated tin, allow water to spill like a waterfall into the pond. Be creative, and figure out what works best for you.
