So, your pond has become inundated with chara. Chara, or muskgrass, can be handled using a variety of methods: mechanical, biological, or chemical. Each of these methods has its advantages and disadvantages.
Chara emits a garlic-like odor when crushed and has a gritty, crunchy texture. Smaller water bodies with good water clarity can be especially vulnerable to large Chara communities, especially those with excessive nutrients.
Mechanical removal is the simplest and cheapest method of control, as it requires very little upfront cost. Depending on the size of your pond, using a garden rake tied to a rope can be an effective method to remove chara. Pick zones that are high-use like swimming, fishing, or boat launching areas. Toss the rake into the water while holding the end of the rope, and once the rake has sunk for a few seconds, retrieve the rake by pulling the rope. Once you’ve pulled the rake back to shore, remove the chara from the teeth and dispose of it away from the water. Repeat this process until the desired amount of chara has been removed from the area. This method will not completely remove chara from the pond, as broken fragments can regrow. As an added bonus, you will get a good workout using this method.
A rope and rake can be a tool to physically remove Chara from a pond, but the work is labor intensive and the benefits relatively short lived.
Biological removal is less labor intensive and works passively, but it can take a while to see results. This involves stocking grass carp into a pond and allowing them to eat the vegetation. It is recommended that pond owners stock only 5 – 10 grass carp per surface acre. Grass carp purchased and stocked in Oklahoma waters should be triploid to prevent natural reproduction. Grass carp are nonnative and are one of the first fish to leave a pond if water is going over a spillway. If stocking grass carp, be sure to have fencing across spillways so these fish are not lost in heavy rain years. Grass carp will typically have little effect the first year of stocking as they are smaller in size.
The last removal method is chemical, which involves the use of herbicides. This is typically the most expensive method of removal, but it can have some of the quickest and longer lasting results. Always read the label of any product and follow the directions before use. Applications should never cover more than one-fourth of the surface area of a pond at a time. This will prevent too much vegetation from decomposing and will minimize the risk of a potential fish kill due to the loss of dissolved oxygen. Products containing copper sulfate, copper chelated complexes, or alkylamine salts of endothall as the active ingredient are all effective at treating chara. They come in liquid or granular forms, which allows for multiple dispersal techniques. Chemical treatments typically must be reapplied each year if regrowth becomes a problem.
No method listed above is a magic bullet to get rid of chara for good. Keep in mind some aquatic vegetation, including chara, is needed for a healthy ecosystem in a pond, so complete eradication should never be the goal.