The Do's & Don'ts of Copper Sulfate in Ponds

Copper Sulfate is the most used, and the most economical algae control available for ponds and lakes.

By  •  • 5 minute read

James is a private pond owner. He owns a 2 acre pond in his backyard. He called and asked if copper sulfate was the best way to go regarding pond algae. He woke up with his pond covered in algae and aquatic weeds and needed to take care of it. We shared with him that it was an excellent way to kill many different strains of algae. He asked if he bought it online if he could do it himself. We explained he needed to check with codes in his state to see if was legal to apply himself. But having a professional apply the treatments would be less hassle and give him quicker results.

Depending on whether the algae is growing up from the bottom or simply floating on the top will determine what form of copper you would want to choose. Bottom algae is best treated by granular forms such as Cutrine Plus. Floating algae may need a liquid mix of copper such as Sepro’s Captian.

However, simply spraying with a liquid copper product may not work and can often kill only the top portions of an algae mat. Strong jets used with mixing tanks on boats with the spraying power of your garden hose work well to inject the copper deep into the mats and break apart the algae for a complete kill. Liquid copper becomes diluted as soon as it is touches the water.

That’s why Sepro’s Captian XTR would be the best choice for most stubborn algae. Their formulation adds a sticky substance called a tacifier or surfactant. This gives the copper the ability to last longer and penetrate into the algae cells for best kill available on the market today.

Copper sulfate is most efficient in water temperatures of 60°F or higher. However, we use discretion with this control method because high concentrations are toxic to fish and food organisms.

Got fish? If there are fish in the pond and the algae and aquatic plants cover a pond suddenly, copper treatment is not advisable. The treatment will likely cause a sudden, algal die-off causing an oxygen depletion that could result and the dead algae decay and the fish will suffocate. Treating only one third of an area at over 48-72 hours will help avoid crashing your oxygen levels.

Have you ever wondered what gets rid of algae in your pond or lake? There are a few things, but Copper Sulfate is the most used, and the most economical algae control available. Copper sulfate (or Copper Sulphate) is an artificial compound that combines sulfur with copper. It’s made up of bright blue crystals (once known as Blue Vitriol or Bluestone) that dissolve in water.

Don’t let its beautiful color fool you; it can be toxic depending on the copper content. It’s usually only harmful if it’s consumed in large doses. So if it gets on your skin before it’s diluted, just make sure you wash it off very well. The toxicity is what kills the bacteria, algae, roots, plants, snails, and fungi.

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Other Ways to Apply Copper Sulfate

  • By Spraying Solution on Water Surface: You dissolve the minimum required dose of in water and spray the solution evenly over the pond or lake.

  • By Broadcasting: Dry Copper Sulfate can be distributed on the water surface by a properly equipped boat. An air blower can be used to blow these crystals over the surface of the pond. When applying, the wind direction is an essential factor.

  • By Injection in Water: A solution can be made with Copper Sulfate that can be injected into the water via a weighted tubing.


  • Low cost
  • Needs to be managed by a professional due to it being hazardous
  • Copper sulphate is the most widely used, and most economical algae control available
  • It can kill algae, bacteria, roots, plants, snails, and fungi
  • If too much is used, it can deplete oxygen leading to fish kill
  • It is both an effective algicide and a parasite treatment
  • Copper sulphate is most beneficial in water temperatures of 60°F or higher
  • Do not use in koi or trout ponds
  • Use in swimming pools for a 90 day algae treatments

Fun Facts

(Disclaimer: we have not tried these and we do not condone the use of copper sulfate in these ways. They are for historical and entertainment purposes.)

  • Has been used as a cure for warts
  • Has been used as toothache relief
  • Has been used for athlete’s foot or tinea
  • Has been used for toenail fungus
  • Has been used for canker Sores

Taking care of your lake or pond is not a luxury, it’s a necessity. As your local pond management professionals, we’ve been there. Let us help guide you as a member to protect, plan, and preserve your pond or lake if you live in the Charlotte NC, Asheville NC, and Greenville SC areas.

Get started. And become a member today!

Filed in: Algae Aquatic Weeds , Pond Management , Lake Management , Charlotte, NC & Greenville SC • Tags: Aquatic Weeds , Algae , Pond Management , Charlotte NC & Greenville SC

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