Pete Lane, Montgomery County Agriculture and Natural Resources Agent
For several years, preformed plastic pools have been best-sellers at garden centers. Liner kits of plastic or rubber are available for those aquatic architects who want a unique pool design. Pumps and lights offer splash and sparkle to complement colorful fish and plants. However, water garden displays have lured many who didn't realize what they were getting into.
It's not just like keeping potted plants or an aquarium. The outdoors has a wider range of temperature and light conditions, and fallen leaves and dirt will create challenges that don't occur inside. Pets, birds and wildlife are attracted to the water--or sometimes to its fish. And while visitors like frogs or butterflies may be attractive, others, like mosquitoes or snakes, have less appeal.
In the summer, the dark color and limited depth of pools makes them warm nurseries for algae. Leafy plants can limit algae by shading the water and absorbing nutrients, but the growing season begins earlier for algae than for plants. Without timely removal and judicious use of algaecides, algae will clog pump filters and turn a pool into pea soup.
Some of the more colorful flowering aquatic plants are tropical and must be moved indoors to have any chance of over-wintering. Others are annuals. Even hardy perennials such as iris may need to be shifted to deeper water to survive the winter. Plants that do pull through the winter will need careful removal of dead leaves each spring.
Dirt and dead leaves from plants both inside and outside a pool accumulate on the bottom to create a layer of muck. The decay process ongoing in the muck can deplete the pool of oxygen and kill fish. It's a year-round threat, because while decay slows down in cooler temperatures, oxygen production by plants does the same.
Fish are attractive additions, but they do complicate matters. They accelerate the accumulation of muck on the bottom and may stir it up with their foraging habits. Many survive or even thrive in ice-covered water, but they could succumb to suffocation when plants die and light is cut off under snow-covered ice. Raccoons and cats pursuing fish create havoc both in and around the pool.
Fish may eat mosquito larvae, but they may also eat plants. And they might not eat algae. Without fish, calm pools will need larvaecide tablets for mosquito control. A small fountain or cascade will inhibit mosquitoes, but a small filter can cause lots of down-time for those features.
Local water gardening clubs are good places to learn more about the joys and frustrations of landscape pools.
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