AlgaeSTOP is a fast-acting pond algaecide formulated to control nuisance algae in ornamental ponds, koi ponds, fountains, aquariums, and water gardens. It helps stop green water, string algae, hair algae, and blanket weed by targeting active algae growth and supporting clearer, cleaner water.

Using an industry-leading concentrated formula, AlgaeSTOP works directly on existing algae blooms by disrupting algae growth processes, including photosynthesis and reproduction. As treated algae die off, they can be removed through filtration, skimming, or manual cleaning to help restore pond clarity.

AlgaeSTOP is ideal for self-contained pond and fountain systems where algae growth can quickly affect water appearance and maintenance needs. A weekly maintenance dosage helps prevent new algae from returning, making it a practical solution for routine pond algae control.

When used as directed in a well-aerated, contained pond system, AlgaeSTOP will not harm decorative fish or aquatic plants and is safe for pumps and filtration equipment.

Application Rate

1 oz

Treats up to 600 gallons

2 oz

Treats up to 1,200 gallons

4 oz

Treats up to 2,400 gallons

8 oz

Treats up to 4,800 gallons

How to use

It is a violation of Federal law to use this product in a manner inconsistent with its labeling. For ornamental, synthetically lined pond use only, where all water is contained without any outflow. Before use, read and follow all label directions. Use only in established ponds at least four weeks old. Note: Warm weather – before using, make certain that the pond has vigorous aeration, i.e., an aeration device to avoid fish loss due to low oxygen levels. When algae is controlled and removed by the filter or settles to the bottom of the pond, the oxygen level may drop to harmful levels if adequate aeration is not provided. In warm weather, pond water carries much less oxygen. Therefore, when using during warm weather and high water temperatures, vigorous, 24-hour aeration is required for the duration of the treatment. Do not shut off pond pumps and aeration devices at night. To ensure accurate dosing, determine pond volume before use. Do not overdose. Add 1 fl. oz. (30 ml) for each 600 gallons (2,268 L) of pond water. Thoroughly mix into pond water by adding near the pump outflow or aeration device. It can be mixed in a bucket of pond water and dispersed evenly around the pond. Repeat dose every three (3) days until algae is controlled. Be prepared to siphon out dead filamentous algae. Once algal/algae is under control, dose weekly. Weekly doses will control algal/algae and reduce maintenance. Do not use with freshwater crustaceans, including: shrimp, crabs, and lobsters. Safe for use in ponds containing decorative fish, aquatic plants, pets, and wildlife when used as directed.

AlgaeSTOP Label

AlgaeSTOP SDS