The water plant Elodea densa is also known as Egeria densa or Anacharis densa. It is a submerged plant with an indefinite potential to spread. Elodea oxygenates water, so pond keepers grow it in ornamental fish ponds to make the pond hospitable for fish.

Elodea grows best in water at least 8 inches deep. Algae compete with Elodea for nutrients and sunlight. To start Elodea in a pond that is covered by algae, remove as much algae as possible. This will give the Elodea room to get a foothold.

Elodea needs to grow in an open sunny area. Elodea thrives in USDA zones 9 to 10. In these zones, which have average minimum temperatures above -6.67 degrees Celsius, Elodea is an evergreen or semi-evergreen. In zones 7 to 8, where the lowest temperatures range from -17.8 to -6.67 degrees Celsius, Elodea is a perennial. Farther north, remove Elodea from an outdoor pond and protect it from winter weather.

Fertiliser boosts Elodea growth--the best fertiliser is fish waste. Keep ornamental fish with Elodea.

As the plant expands to the limits of the pond or container, thin the Elodea by removing sections. This will keep it vibrant.