Nov. 1 2006 12:00 AM

Photo courtesy: Aquascape

If youve found installing ponds and water features to be a successful venture, you can take that success to the next level by beginning to maintain ponds as well. Maintaining a pond in warm weather is one thing, but autumn is here and winter is close behind. If you work in a freeze-zone, your customers ponds may be about to freeze over. This requires different and additional maintenance they may not want or know how to deal with, giving you the perfect opportunity to offer your services.

The number-one factor to consider when winterizing a pond is the same as when you winterize an irrigation system: water freezing. When water freezes, it expands. If its trapped in a pipe or other enclosed area, the expansion of the water as it turns to ice can cause the pipe to crack.

First, consider the type of liner the pond or water feature was contructed with. Rubber liners are capable of expanding to more than 300 percent of their normal size without breakingthis means that water freezing inside wont be a problem. However, if you have a concrete-lined water feature, you may have to pump all the water out. Concrete wont expand with the ice and instead can crack.

Even if a water feature isnt lined with concrete, some customers may want to shut it down in winter anyway. If this is the case, make sure the water level is below the depth of the skimmer, pipes, and filters. Blow any remaining water out of the pipes, just as you would an irrigation system, and drain any remaining water from inside the skimmer, waterfall box, etc., so these components dont crack.

You should also remove the pump. However, a pump shouldnt be stored dry over winter. A pumps seals swell when wet, and can crack if they dry too quickly. Cracks in the seals can make the pump burn out faster, says contractor Bob Wambach, president of Ponds and Patio, Inc., Monona, Wisconsin. I recommend storing pumps in a bucket of water someplace where it wont freeze, like a basement.

If a customer wants to keep his water feature running all winter long, try dropping a de-icer into the water near the skimmer to prevent water around the skimmer from freezing. Chunks of ice can clog the skimmer and prevent water from getting to the pump, a problem which again can cause the pump to burn out.

Waterfalls can be especially beautiful in the wintertime, because they sometimes create amazing ice sculptures on the surface. When kept running all winter, the movement of the water will keep it from freezing inside. However, most waterfalls havent been designed for winter. Ice can build up in places and create barriers that divert water out of the pond, disrupting its normal spill path. This can significantly lower the water level until all of the components are running dry.

You need to keep an eye on the water level all winter long, says Don Leyn, president of Irrico Sales, Inc., Englewood, Colorado. You can lose more water out of a pond because of ice diversion in winter than because of evaporation in summer.

A few manufacturers make low-temperature, autumn/winter beneficial bacteria that can be added to ponds when the weather starts to get chilly. While this is an especially good idea in ponds that contain fish because it helps maintain a clean environment, it can also be used in water features that dont contain fish. The bacteria will consume the dead leaves and twigs that build up in a pond throughout the winter, giving you less to clean up come springtime. A leaf net can help keep this kind of organic matter from blowing into the water feature in the first place.

Any tropical plants in or around the water garden should be moved indoors to survive winter. If they are in plant baskets, plants that remain in the pond should be moved to lower pond shelves. These plants should also be trimmed back to minimize the buildup of dead plant product that will have to be cleaned out in spring.

If a pond contains fish, the key to winter maintenance is oxygen. The pond wont freeze solid or become too cold for fish. Those are myths, says contractor Rob Dietter, Dietter Water Gardening, North Haven, Connecticut. Its not a water depth issue, its a gas issue.

Fish need oxygen to breathe. Additionally, the waste they produce creates other gases, which could build up and eventually suffocate them. Water takes in oxygen and releases other gases at the surface of the pond. Some parts of the surface must be exposed to air and not frozen over for this exchange to take place. Meaning: there have to be holes in the ice.

If water is moving, it cant freeze. Therefore, an aeration kit at the surface of a pond will help keep a hole in the ice. De-icers are another good option, heating a small area of water just enough to maintain a hole. You dont want to heat the entire pondthis will cost an enormous amount in terms of energy, as well as confuse the fish. Fish are used to going dormant in cold weather; the best advice is to just let them.

Simple steps like these are really all it takes to properly prepare a pond for winter. The more winterizing you do, the easier it will be to kick-start the pond or water feature again in springtime.