This summer we decided to build a garden pond. I figured we could do it “simple” and “quick” using plastic livestock water tanks… but it has become a bit more complicated over the course of construction! Below is the final-ish plan for how our pond is set up. It includes a main, deep pool for fish, and a second pool mostly filled with various materials to act as a natural bog or swamp filter.
This design is based on a combination of sources, from pond books to internet forums to various other info. While it may not be the best/cheapest/simplest method, I’m hoping that it will manage to combine natural filtration, low-ish maintenance, and an interesting look! The main fish pond should be deep enough to over-winter fish in Minnesota, perhaps with the addition of a bubbler and/or heater.
Transporting stock tanks is always entertaining…
After extensive planning, we started digging the holes.
Thanks to some research, I had already determined that our garden used to have a duplex in the 1800s, which was at various times home to a saloon, an election polling place, and a local con artist. While digging the smaller hole, we ran into the limestone foundation.
I dug up an entertaining array of artifacts from the old rubble, including bottles, pottery, coal, a narrow-gauge railroad spike, a knife blade, and an empty .38 revolver casing!
After getting the holes finished it was time to install some plumbing for the pump and filter system. I added heat tape to the pipes since there’s no easy way to drain them. The pump will probably stay turned off in the winter and I have a thermostat-controlled switch to turn on the heat tape if the ground temperature drops too low.
The pump is also located underground in a waterproof box. This will eventually have a bench on top of it.
Next came the stock tanks. The pond holes ended up quite a bit larger, as we decided to just use the tanks as the bottom of the pond and extend everything with flexible liner. This might be a bit redundant, but it does make the bottom few feet of pond extremely leak-resistant!
Getting a square liner to fit an oblong hole is a hassle, and results in a lot of unsightly creases. I did my best to reduce or hide these, but still ended up with some ugly folds (pic below is not the final liner arrangement).
The bog filter received a plastic shelf raised off the bottom with brick (which is safer for fish than cinderblocks or limestone, which can leach lime into the water). Below the shelf is a PVC diffuser for incoming “dirty” water. Above the shelf goes gravel and dirt for the swamp in various layers. The two pipes at right are cleanouts to help deal with the inevitable mud that will make its way into the bottom void area.
Coming soon, some more details and photos with actual water in the pond!