• Ponds add to the landscape but require maintenence to remain healthy.man made pond image by Wimbledon from Fotolia.com
  
  A pond adds a sense of tranquility to the backyard garden. The water attracts insects such as butterflies and dragonflies to your yard, as well as frogs and birds. Whether you've decided on a large or small pond, a good deal of maintenance is necessary to ensure your pond remains healthy. Although there are many natural remedies, at times a chemical solution is necessary.
  
  

Algaecides

• A little algae in ponds is accepted; too much can harm pondlife.Mexican Papyrus image by Towards Ithaca from Fotolia.com
  
  Algae are a type of plant that grows in or around water. String algae form long strings that hang from rocks or attach to plants or other parts of the pond. Other types of algae grow along the sides of the pond and float in the water turning it green. This plant robs the pond water of oxygen and can suffocate fish and other plants. Like any plant, algae need light, nutrients and water to thrive. Controlling the amount of light and nutrients in the water will slow the growth of algae but not eliminate it. You can add chemicals to the water to kill the algae. Unfortunately, these chemicals may damage the other plants in your pond. Herbicides used for algae include copper sulfate, iron salts and benzalkonium chloride. These chemicals are readily available at garden supply or specialty stores as ingredients in pond care products.
  
  

Clearing Agents

• Clear water allows you to observe fish and other wildlife.cool clear water image by Louise McGilviray from Fotolia.com
  
  Over time, ammonia and nitrogen levels may build in your pond causing the water to appear cloudy. Aside from diminishing the aesthetic look of your pond, fish and plant life suffer from the high levels of ammonia. Cloudy water may also indicate a high level of sediment in the pond water. While this may not kill the fish, according to the Virginia Cooperative Extension, it does increase water temperatures and lowers the oxygen content of the water, which can damage your fish or plants. Several products on the market clarify pond water, such as aluminum sulfate and agricultural gypsum, according to the Ohio State Department of Natural Resources.
  
  

Mosquito Control

• Mosquitoes lay their eggs in ponds.mosquito image by Martin Sevcik from Fotolia.com
  
  Mosquitoes will lay eggs and reproduce in any stagnant body of water, including the backyard pond. Mosquitoes prey on humans and spread the West Nile Virus. While fish may eat some of the mosquito larva, responsible pond owners ensure their garden water feature does not become a breeding ground for these insects. Take care to protect fish and plants when treating ponds for mosquitoes. Bacillus thuringiensis, or Bt, is a chemical commonly used to control mosquitoes. Bt produces a protein that attacks the insect's stomach lining. As sunlight decreases the effectiveness of this chemical, it's necessary to repeat applications every few weeks until no further larvae is present.