Pond Care Frequently Asked Questions


Q. What do I do with the dead cattails? Can I cut them down or dig them up?

A. There is no need to dig up the dead cattails. Just cut the plants at the ground level and let them decompose. However, please wait 3 - 4 weeks after herbicide application to ensure the product has translocated to the roots of the plant before cutting.

Q. Are any SePRO Pond Products restricted from sale in my state?

A. For our customers in New York, New Jersey, Connecticut, Maine, California and Washington state, SePRO is currently limited in the direct selling of regulated aquatic products. Revive and SePRO Blue can be purchased and used in all states. Please contact your SePRO pond advisor for more details.

Q. Can I use SePRO aquatic products in my aquatic garden?

A. Aquatic gardens (smaller than 50' x 50') can be effectively treated with SePRO pond products. Simply multiply the length x width in feet and divide by 43,560. Multiply this number by the recommended rate of product per acre.

Q. Do I need a permit to apply products in my pond?

A. Always check with your state and local regulations, but in most cases a permit is not needed for privately-owned ponds. We recommend checking with your local extension agent prior to applying products. You can visit the United States Department of Agriculture web site for information on how to contact an extension agent in your area at:


Q. How can I control mosquitoes?

A. Start by controlling algae and weeds. Most mosquitoes thrive in water that is stagnant and filled with algae and weeds. By reducing the amount of algae and weeds, you will reduce the mosquito population. After reducing the algae and weeds, you can also add top-feeding minnows to help control the mosquito population. In clearer water, they will be able to access and feed on the mosquitoes. There are also mosquito insecticides that can be used to control mosquitoes.

Q. How do I know what type of weed I have in my pond?

A. Aquatic plants are identified based on their location in the environment. See the most common aquatic weeds by clicking on the "Weed ID" link at the top of this page for detailed pictures and descriptions. If you have some trouble with identification, most plants can be identified over the phone by calling your SePRO pond advisor.

Q. I have 8 feet of shoreline covered in cattails. Can I control half of these cattails and leave the other half to grow?

A. Yes. With AquaPro you will only control the plants you spray. If you do not directly spray the cattails they will not be affected by the treatment. AquaPro is a contact product.

Q. I haven't had a weed problem in the past; where did it come from?

A. Waterfowl and roaming animals carry floating plants such as duckweed and watermeal from pond to pond. Submersed vegetation can get into to your pond the same way, or be washed in from other ponds. Some people introduce plants into their ponds for aesthetic purposes and find, in a short time, these non-native species over take the pond and need to be removed.

Q. I haven't had problems with my pond in the past; what has changed?

A. Eutrophication is the natural aging process of a pond. A pond begins as a well-balanced ecosystem of plants, fish and invertebrates. Over time, however, watershed run-off often produces nutrient overload, which can contribute to an overabundance of vegetation, reduce invertebrates and crowd out fish populations.

Q. Why is my pond cloudy during the summer and clear during the winter?

A. Planktonic algae blooms, which take place in warm water during summer, are not present in cold water during the winter.

Q. Why is algae a problem in my pond?

A. Excessive nutrients in bodies of water are becoming problematic in promoting algae growth. Blue-green algae may cause illness and in some cases fatalities in pets, livestock, and wildlife. Exposure to or ingestion of this algae may also cause a variety of discomforts in humans. Algae contamination in drinking water can discolor the water and cause unpleasant taste and odor, and may impart a distasteful flavor to fish. Decomposition of decaying algae in late summer commonly causes a fish kill due to rapid dissolved oxygen depletion.

Q. If I use aquatic weed and algae control products will they harm my fish, pets or the local wildlife?

A. Herbicides labeled for aquatic use are non-hazardous to fish, pets and the local wildlife when used in accordance with the product label.

Problems, should they occur, are caused by misuse of herbicides, such as:

  • Exceeding recommended label rates
  • Exceeding application recommendations
  • Using products not labeled for aquatic use

Q. How do I know if I have duckweed on my pond?

A. If you’re not sure what kind of aquatic vegetation you’re dealing with, utilize the LakeLawnandPond.com Weed Identification interactive page for assistance.

Q. What’s the best way to prevent duckweed from returning?

A. Prevention is the key to avoiding costly control measures to eliminate a nuisance duckweed problem. Nutrient reduction and getting some motion in the water through a technique such as bubble aeration are two key preventative techniques. If duckweed does reappear, it is much easier to control the tiny emerging plants than the mature plants; so the best time to take action is at the first sign of infestation.

Q. Where did all this duckweed come from?

A. Duckweed is moved from pond to pond by animals and waterfowl such as ducks and geese. Once duckweed is introduced into a waterbody, it can spread rapidly if conditions are right. Ideal growing conditions are still or slow-moving water that is high in nutrients such as nitrogen and phosphorous.

Q. How can I tell if I have algae or duckweed?

A. There is a simple test: submerge your hand in the plant matter. If the mass separates, it is probably duckweed or watermeal. If the mass does not separate, it is probably algae. Algae is usually slimy and stringy and forms mats on the surface of the pond. Duckweed appears to form mats, but is a system of small plants the size of pencil erasers that float on the surface of the water. Duckweed resembles clovers floating on the surface of the water and has small white roots hanging from the bottom of the plant.

Q. I have a "green scum" on my pond; what is it?

A. Green water or "scum" on the top of your water can be any of several things: duckweed, watermeal, or algae. Frequently these are mistaken for each other. Duckweed are very small floating leaves with a small root while watermeal resembles green sand. Filamentous algae form dense mats that float on top of the water and planktonic, or blue-green algae, give water a 'pea soup' consistency.