Algae can be a huge headache for those who own small water features and ponds but finding easy, efficient pond algae solutions aren’t as difficult as you might think. In some cases, an algaecide, such as SePRO’s Captain can be the best option to remove many common types of pond algae.


What Is Captain?

SePRO’s Captain is a copper algaecide. Copper has been used for more than 70 years as a pond algae solution and there are actually several different types of copper algaecide. Some copper-based algaecides are granular and known as crystallized copper, while other copper algaecides come in liquid form or chelated liquid form.


Crystallized or granular copper algaecides tend to be less effective for algae control than liquid copper algaecide. This is because the crystals can drop quickly to the bottom of a pond, usually within just 24 hours. Liquid copper, on the other hand, will remain suspended in the pond water for a longer period of time, which allows it to come into contact with more algae.


Captain uses what is known as double-chelated copper. Chelated copper is bonded to another element, which prevents the copper from dissolving as quickly. It’s kind of like a coating that slowly dissolves and allows the copper to work for a longer time in your pond water.


What Can Captain Treat?

SePRO’s Captain can be used to treat ponds with an overabundance of planktonic or filamentous algae as well as muskgrass. Let’s take a quick look at these types of algae and how they can damage your pond ecosystem.


Planktonic Algae – If your water has transformed from a lovely blue hue into more of a vat of pea soup, planktonic algae probably is the culprit. Small amounts of planktonic algae can be harmless, but if oxygen levels in your pond drop, this algae can propagate and cause problems.


Filamentous Algae – If your pond is covered by what appears like a blanket of green muck or fur, you have a filamentous algae problem. Filamentous algae are a single-cell organism, but it joins together to form long strands. With a smaller water feature, you might be able to remove most of the filamentous algae manually, but this can be very time-consuming. For larger ponds, Captain can be a better and easier option to consider.


Muskgrass – Many people mistakenly identify muskgrass (also known as Chara) as a plant, but it is a type of multicellular algae. They have an unpleasant odor and can be difficult to remove from your pond. While skimming out muskgrass can remove much of the algae, any bits left behind will continue to grow and quickly. Using an algaecide such as Captain can be the easiest way to get rid of muskgrass.



Got Fish? Read This Before You Use Captain

In general, Captain is safe for livestock, wildlife, pets and people. However, if your pond is stocked with koi, goldfish or trout, Captain is not a suitable pond algae solution. Captain also is not safe for some aquatic invertebrates. For koi ponds or ponds stocked with trout, we recommend treating the water with Rush® instead.


Additionally, Captain cannot be shipped to several states, including Alaska, California, Connecticut, Maine, New York, New Jersey or Washington. If you live in these states and are having trouble with floating green organic matter or weeds, please give us a call or send us an email and we will help you find pond algae solutions for your specific pond issues.


How To Use Captain

Algaecide needs to be handled with care, and you need to wear personal protective equipment (including eye protection) and chemical-resistant gloves when applying this to your pond. Captain and other algaecides can cause skin irritation and are harmful if inhaled and can cause eye damage so please take care and follow all instructions carefully.


When applying Captain, you only treat the algae and not the entire pond. In some cases, if much of the pond is covered with algae, it is best to only treat a few areas at a time. Spray only onto ½ to 1/3 of the surface area of the pond at a time. Treating all algae across the entire surface area at one time can cause oxygen depletion and result in harm to your fish. Again, do not use Captain in ponds stocked with koi or trout.


You also need to consider spray drift management, so be sure to monitor the wind direction and wind speed. Do not apply Captain if the wind speed is greater than 15 mph. Captain is most effective when it is applied in bright, early morning sunlight under calm conditions and when the water temperature is at least 60 degrees.


Be sure to read the label for complete use directions, we also have a link to the product information at If you have any questions about Captain or how to use Captain, please do not hesitate to contact the team at Healthy Ponds at any time.


After Treatment: Preventing Future Algae Issues

Once you’ve used Captain as your pond algae solution, it’s time to think about preventing future algae growth. Algae multiply because the conditions in your pond allow them to do so. Ponds with low oxygen levels are particularly prone to algae blooms, so keeping oxygen levels up is crucial.


One way to prevent drops in oxygen levels is to prevent run-off from entering your pond. You can create a protective barrier of beneficial plants to keep the shoreline strong and to prevent runoff from heavy rains. Taking good care of your surrounding lawn also can help as healthy grass and soil soak up rain more efficiently, which reduces runoff.


When cutting the grass around your pond, we recommend bagging it up and disposing of it in an area where it cannot enter your pond. Grass often is treated with pesticides that contain nitrogen and phosphorus and debris and runoff from these lawns can enter your pond and upset balance in your pond ecosystem.


Using an aeration system also can help keep oxygen levels high, and a bottom aeration system typically works best. This circulates the water in your pond, keeping temperatures down and you can even use a filtration system to remove excess animal waste. Waste from fish, wildlife and livestock also can affect the oxygen levels in a pond. Keeping an eye on your fish population also can help ensure that your oxygen levels are safe.


Using a monthly treatment of beneficial bacteria also can be a good idea, as these bacteria consume excess nutrients in your pond and can prevent many common pond issues. We have several all-natural beneficial bacteria products that can help reduce excess nutrients and may prevent the growth of floating green organic matter.


Pond algae control can seem overwhelming at times, but our pond algae solutions, such as Captain, can remediate most algae problems quickly and easily. In addition to Captain, we have several other pond algae and weed control chemicals. To find the right product for your pond, we offer free personalized pond treatment plans for any size water feature at

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Why Choose to Autoship?
  • Automatically re-order your favorite products on your schedule.
  • Easily change the products or shipping date for your upcoming Scheduled Orders.
  • Pause or cancel any time.