Water gardens give gardeners more space to plant and a chance to experiment with different aquatic plants. When planning the water garden, dig it deep enough the first time. While bog plants need only a few inches of water covering their roots to grow, other plants like water hyacinth need deeper water to float. Add a fountain, bubbler or waterfall to keep the water moving so mosquitoes aren't a problem. Fish can stay in a pond over the winter as long as there is a hole in the ice for gases to escape and the water doesn't freeze solid.
Create a shape for the pond using the hose. Irregular curves suggest a naturalized informal pound. Geometric shapes like squares, circles and rectangles are more formal in design.
Dig the outline of the pond using the hose as a guide. Remove the hose and continue digging to the required depth. Koi, a Japanese fish often used in ponds, require water at least 3 feet deep. Goldfish need 24 inches, so the water doesn't heat up or cool down too fast. Water lilies also need 24 inches.
Dig the sides straight down so predators won't try to wade in after the fish. Plan for bog plants by leaving shelves of dirt to support the plant. Bog plants prefer 3-6 inches of water over their roots. Deeper water drowns them.
Lay the scrap wood over the pond from one edge to the other. Put the carpenter's level on the wood. The pond should be very close to level. If it's not, the water will look like it's tilted, coming up further on the shorter end of the pond.
Remove rocks, sticks and tree roots. They can puncture the vinyl liner of the pond. Place 4 inches of builder's sand over the bottom of the hole.
Lay the vinyl liner in the hole, adjusting it so there are as few folds as possible. The liner should be large enough to completely cover the hole plus 6 inches over the edge.
Fill the pond slowly with water. Adjust the liner to remove wrinkles as necessary. Rim the edges of the pond with rocks, bricks or stones to cover the liner. Wait at least a week before planting.
Install the pond pump with fountain attachment. Exactly how you do this depends on the pump make and model. Generally, you push the fountain attachment onto the water outflow stem. The fountain attachment should have a tube long enough to reach a few inches above the water's surface. Place the pump on the bottom of the pond in the deepest part. Make sure the water intake valve is upright. Plug into a ground-fault circuit interrupter (GFCI) outlet.The fountain adds oxygen to the water.
Add plants. Use a variety of oxygenating, floaters, bog plants and water lilies.
Add fish to the pond after the water plants have been established for several weeks. Place the fish in the plastic bag or container they arrived in on the surface of the pond. If it's in direct sunlight, cover with a cloth. Let the water in the bag reach the same temperature as that of the pond, usually 15-30 minutes. Open the bag and let the fish find their way out. A good rule of thumb is one inch of fish for every 10 gallons of pond, so a 1-inch goldfish will become 6 inches long in a year.