4000 gallon pond dug with a mantis tiller, and coming out of its first fish-keeping winter, its second winter over all.
A skilled aquarium keeper who understands how to turn a saltbucket into a particulate pot-filter with a little floss, a few rocks, pump, and hose can get along pretty well with an 8 foot pond. But should you want to go larger, Savio makes excellent equipment. Try pondliner.com for a good place: its customers are quite pleased with it, and should you have a major pump go, they will ship to you ASAP. I've found their recommendations to be spot on, including what they advise against doing (like splicing the liner). Overbuy liner: you'll find a thousand uses for it.
My own system is a swimmingpool sized skimmer, with a 4" hose headed to the other end of the 20x15 pond for a 3' tall waterfall weir done up in native stone. We're still landscaping: it's an undertaking. But a lot of fun. I will also advise floating rings (we use irrigation hose connected to a doubleended hose barb) with water hyacinth or the like, which provides shelter, serves as a refugium, moderates summer temperatures, and generally stays out of your skimmer that way. Fish can hide under it if a heron lands on the pond edge or a raccoon shows up.
Chemically, it's easier than keeping a swimming pool: just buffer after it rains and test periodically. And of course clean the filters. Plants help. An auxiliary pot-filter helps out during high summer algae fest. I have a uv light and that also helps greatly: it keeps the water clear so you can appreciate your fish. Fish sleep through the winter and require no care to speak of, except you need to keep special heaters going for them in my area.
How we dug it...we laid out garden hose in the pond shape we wanted, got a garden tiller, and churned up that outline, working toward the center. We shoveled the dirt into a rising berm and then brought in more dirt to raise the whole yard in hummocks with a winding path, gazebo, etc. Two person job, nothing worse than pushing a wheelbarrow.
The waterfall sound mitigates the traffic sounds and our pond yard is demonstrably 10 degrees cooler than the front yard in summer.
We run the water fall day and night. It is the filter: big Brute sized bin with fiber inside. Fish have been disease and parasite free, and we got them as 3.50 items at the local feed store, one 30.00 fish (platinum butterfly fin), and will get a red-and-black this spring. But all in great shape.
