Najas Grass and Hard Water

Species

• Approximately 40 species of najas grass exist throughout the world. Many najas grasses are native to Africa and Asia, but five species grow in the Southeast United States. Among the world's najas species are southern naiads (Najas guadalupensis), European naiads (Najas minor) and bushy pondweed (Najas flexilis). Najas grasses feature long, narrow stems with small, 1-inch-long leaves. All najas are submerged plants, but each variety features different physical characteristics. Southern naiads and bushy pondweeds have pointed leaf tips, while European naiad leaves have saw-like edges. Najas grasses grow in brackish freshwater environments.

Problems

• Many aquarium owners place najas grass in their tanks since these submergent plants require a minor amount of maintenance for survival. However, pond owners view najas grasses as weeds. The growth of najas in a natural pond harms the pond's ecosystem by causing discoloration and outcompeting other species for nutrients from the pond's water. Also, if pond owners want to use their pond for fishing, their fishing hooks oftentimes get entangled in the pond's weeds. According to the University of Georgia Warnell School of Forestry and Natural Resources, najas growth has become a rampant problem in ponds throughout the Southeast United States.

Removal

• Several methods are available to pond owners for eliminating undesirable najas grass growth. One of the simplest methods is physically removing the grasses. Nontoxic dyes on the water's surface limit the amount of sunlight a plant receives, and mechanical weed removal devices chop up aquatic weeds. However, Texas A&M University's Agrilife Extension program warns that physically removing najas grass only offers temporary relief, as these grasses are able to regenerate from any remaining roots. Another method is stocking grass carp fish in ponds; grass carp feed on aquatic grasses such as najas. This method usually takes at least one year before pond owners see results.

Hard Water

• Hard water is water with a high amount of calcium and magnesium nutrients. Removing calcium and magnesium nutrients from water is known as “softening the water.” Ponds and lakes receive hard water from water streams that pass by calcareous rocks such as chalk or limestone. Many aquarium owners frown on hard water since this type of water clogs up the organs of the tank's fish species, especially fish from tropical locations where water is usually soft. However, hard water benefits some plants, including najas grasses, by lowering sodium concentration in soil. Excessive hard water also causes najas grass to grow by offering more calcium and magnesium nutrients.