I have always wanted a water garden, but it seemed like a lot of work to set up and maintain, especially here in the tundra of North Dakota where summer is so short. Filters, heater, bubblers, not to mention digging a hole in the ground and landscaping around it. A few years ago I found an easier way: container water gardening.
I used a half whiskey barrel with a plastic liner, which you can find at your local gardening supply store. I added some old fish tank stones to the bottom, filled it up, and let it sit for a few days to warm up.
For plants, I have potted Lily pads, which I left right in the pot. I've had the same lily pads for 3 years and when the weather gets cold I just put them in a fish tank and they winter over in the garage, which stays about 55 degrees. The plant goes dormant and won't have any leaves, but it will wake up when it warms up. At first the pot floated up to the top so I weighted it down with a brick, but now it stays in place. If you looks closely, you can see the square pot:
You can probably find duck weed in your local pond. Just make sure it doesn't cover the surface of your container all the way because you want the sun to penetrate. I usually don't let it cover more then half.
When choosing water plants, it is important to check what depth of water the plants like. For example, the Lily pads like deep water where the whole plant is covered, while some other plants like just their roots covered and the plant grows up out of the water. In this case, you can use bricks to make a little step for the plant to sit on so it is the right depth.
Next comes fish!
Fish are important because they eat insert larvae. The last thing you want is your "pond" to turn into a mosquito breeding area! 2-3 medium size goldfish can live nicely in a container this size. They are much cheaper than koi, yet they can still withstand cooler temperature and their bright color makes them easy to spot. We have three little goldfish in our pond right now. Last year we had a big goldfish, about 6 inches long, but I think a raccoon took him because one day he was gone! I only feed them 2-3 times a week since they are also eating bugs and other things that fall in the water. Unless you live in a warm climate, the fish will need to spend the winter inside as well.
That's all! Container, plants, and fish! I don't use a filter or bubbler, although once a month or so I empty a little of the water out and wash the algae off the sides and the refill it. Some years I had a lot of algae, other years very little.
I hope this helps you create a container water garden of your own! It's a lot easier to maintain than a traditional water garden, doesn't take up much space, and it's a great conversation piece. Just make sure to keep an eye on your tots while they watch the fish.