by Tiffany Martinez
Small garden ponds / pools of 60 square feet or less with fish and water lilies to be overwintered there should be covered, especially if you live in an area with severe winters and frequent below-freezing temperatures.
Pool covers of light, transparent materials use solar heat much the way it is used in a cold frame or greenhouse: The sun heats the air underneath the cover, which slows down the cooling of the water in the fall and delays and lessens ice formation during the winter.
You can cover your pool as soon as you have got it all set for winter. The best time to do this is before the trees lose their foliage. This way you prevent leaves from being blown into the pool in great numbers by fall winds, and you save yourself the chore of fish¬ing them out.
Only materials that let the light through are suitable for pool covers. Glass is not recommended because it breaks too easily. Fluted, fiberglass-reinforced plastic is easy to handle and works very well. It keeps its shape and lasts a long time. You can roll it up in the spring and store it for the following winter in the cellar, where it does not take up too much room. It is available at building supply stores.
Before you go out to buy it, measure how long and wide the cover has to be to extend all the way across the pool and overlap the bank securely. The best way is to measure the length and width of the pool and then add half a yard (50 cm) to both dimensions. When setting up the cover, observe the following:
• The cover has to be mounted at a slant, so that the rain on the top and the condensation moisture underneath will run off. The slanted position also ensures weak but essential aeration.
• The slant should face south because the heat of the sun is utilized most efficiently this way.
• Keep an air pump with attached air stone running in the pool to ensure an adequate oxygen supply. Place the air hose in the pool at a medium depth.
When mounting the cover, proceed as follows: Start at the north side of the pool because this is where you have to erect supports for the higher end of the slanting cover.
Perforated bricks work best for this; they are cheap and are easy to put away again in the spring. Make several piles—the number depending on the width of the pool—at short distances from each other.
Use laths (1×2 inches or 24 x 48 mm) to support the cover. Arrange the laths to form a grate (laths 24-28 inches or 60-80 cm apart).
Now lay the strips of plastic covering over the pool or, more precisely, on top of the laths. It is best to have a strong helper for this; this jobis handled much more easily by two people than by one alone.
Finally, weigh down the edges on the long sides—that is, north and south—with rocks so the wind cannot carry the cover off.