Now I need to figure out an ideal pumping solution, preferably electric on a timer.
How high do you have to lift the water to get it from the catch basin back up into your main pond?
How clean can you keep the water you are pumping?
Will you have AC electricity at the site?
The centrifugal "lawn irrigation" type pumps that many of the manufacturers sell are pretty darn efficient in terms of gallons/kWh and should closely match your requirements? Almost every pump likes "cleaner" water, but some are more tolerant of trash and debris than others.
See if you can get a good sales rep or engineer on the phone or in a chat. I have sometimes gotten excellent people that know their stuff, and sometimes gotten idiots that are just reading off of the same literature I can read on the website.
If you do get a good person, ask about the best "duty cycle" for the pump you are sizing. If they say "two hours on, then two hours off for cooling", then use that info and your desired daily pump rate to size the correct pump for your application. Since you are going to be running this pump long term, you definitely need to utilize "best practices" for whatever style of pump you end up installing.
Good luck on your pond-topping project!
P.S. Glad to see you managed to make some lemonade with the lemons you were handed at your pond.
