It might be tempting to pour some household bleach into your backyard pond to clean it up, but unless the pond is devoid of life of any kind, steer clear of bleach. The purpose of a backyard pond is to create a small wildlife environment for the benefit of animals and insects as well as people. Bleach, which is toxic to fish, plants and animals, is not compatible with a backyard pond's purpose.
Why Bleach is Bad for Ponds
One of the ways to establish life in a backyard pond is to maintain a colony of beneficial bacteria. Household bleach, which contains chlorine, kills bacteria. This is helpful in kitchens and bathrooms, but your backyard pond needs good bacteria to keep algae in check and benefit fish.
Bleach is harmful to visible pond life as well. Plants cannot handle large amounts of bleach, though the chlorine level in tap water will not harm vegetation. Bleach also kills fish, insects and frogs that may be living in and around your pond. Bleach will kill unwanted bacteria and algae, but at the expense of everything else in the pond. Instead, if you have problems with the overgrowth of certain types of algae or bacteria, purchase a pond additive to manage this specific issue.
When It's Safe to Use Bleach
The only time bleach is acceptable to use in a pond is if all plant and animal life has been removed and you intend to start the pond over from scratch. Even in this instance, do not add bleach to existing water. Empty the water, then clean the pond liner or hard mold with a bleach and water solution. Rinse the pond thoroughly, then add fresh water. For the safety of plants and fish, use a chlorine remover to detoxify the water before adding pond life.
You can use a bleach and water solution to clean statues, figurines and plant containers if you remove the items from the pond before cleaning them. Make sure they are thoroughly rinsed before putting them back in the water.
Proper Pond Cleaning
If you have put your pond together thoughtfully with proper planning and research, it should need only minimal cleaning. Algae tends to be one of the biggest problems for pond owners, but instead of using an algae-killing additive, plan your pond in a way that discourages algae overgrowth. Use plants for shading, because algae needs sunlight to grow. Add plants and animals that feed off algae. Use an underwater vacuum occasionally to thin out algae on the pond floor, but be careful of fish and plant roots. Do not overfeed fish; if you do, fish waste can build up too quickly, making water dirty and encouraging algae growth. Clean statues, figurines or pots that are in and around the water. Use a pool skimmer to remove dead leaves in the fall. Drain the pond to winterize it if your area has a cold winter climate.