Mike, for optimum oxygenation & water clarity, you'll want to circulate the entire gallonage of the water garden once every hour to hour and a half. I have a 5,000 gal. garden & pump 4200 gph through filtration & waterfalls 24/7/365.
There's a lot more to keeping your pond clear and low maintenance, but sizing the pump correctly will get you off to a good start. It's a good idea to purchase a pump that's one step higher volume than what you need, as you may get "the bug" to add on. Best of Luck!