Plant-disease expert Dr. Alan Windham of the University of Tennessee Agricultural Extension Service offers advice on preventing pond problems. Algae, whose growth is a common problem, can be blown in on the wind or introduced into your pond when you add new plants. Algae needs sunlight and nutrients to grow, he notes, and most ponds are sited in full sun. Algae won't damage your pond, but it colors the water so you can't see the fish, and most people prefer clear water. There are two ways to control algae growth. The first is to cover 60 percent to 70 percent of the surface with plant material so the algae can't photosynthesize. The second is to use floating plants such as water hyacinths. Algae bloom occurs when the water contains excess nutrients, but floating plants consume the nutrients. If you fertilize your lawn or garden and the fertilizer runs into the pond, algae growth will be encouraged. To prevent this problem, make sure the edge of the pond is slightly above grade. Another way to prevent new algae from growing in your pond is to add a bale of barley straw (figure A), although it won't kill established algae. Barley straw is sold in mesh bags with a lead weight attached to prevent them from drifting. As the bale breaks down over a period of several months, it releases chemicals that inhibit algae growth. Copper sulfate controls algae growth by coloring the water to block sunlight from reaching the bottom. It's safe for most fish, but it may harm water lilies and water hyacinths. Products consisting of beneficial bacteria (figure B) can also help control algae growth. Add a prescribed amount of bacteria once a week for four weeks, then additional bacteria once a month for the rest of the summer. The bacteria attach themselves to hard surfaces such as rocks and compete with the algae for available nutrients. Another solution is to use ultraviolet light. As water is pumped through an ultraviolet light source (figure C), the algae's DNA is disrupted, preventing the plants from reproducing. A water clarifier that uses a low-wattage UV bulb costs less than $100, but the water should be filtered before it reaches the light unit. A UV sterilizer, which kills bacteria and also some pathogens that attack fish, is more expensive. The bulbs are fairly expensive and may cost half the price of the unit, but they should last for a year or more. A typical pond filter (figure D) removes heavy particulate from the water. The filter should be changed or cleaned regularly. A source of electricity is required to run the pump. With a combination of these methods of algae control, you'll never have to change the water in your pond, although water will be lost to evaporation, especially during warm weather. Add water from the garden hose as needed.
GUESTS :
Alan Windham
UT Agricultural Extension Service
5201 Marchant Drive
Nashville, TN 37211-5201
Phone: 615-832-6802
Fax: 615-832-0043
Email: awindham@cru.gw.utk.edu
Website: http://www.utextension.utk.edu
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