Planktonic Algae blooms cause the water to turn a pea-soup green color. Not only does planktonic algae ruin the alethic look of your pond, it can cause a great danger to fish when trying to treat it. What happens is when the planktonic algae dies off rapidly, from either weather change or treating the water with an algaecide, it will deplete oxygen from the water, possibly causing a fish kill if the oxygen depletion is great enough. Although it is not a 100% guarantee to prevent a fish kill, having an aeration system will reduce the possible risk of one.
Using Pond Dye will help to limit sunlight into the pond for algae to complete photosynthesis.
There are several chemical options to control planktonic algae. They should be applied when the algae is actively growing. Applications should begin when algae first appears as long as your water temperatures are above 60°F. Unless steps are taken to reduce the overall nutrient load, multiple applications may be needed for full season control.
Chemical Application Best Practices
Anytime you use chemicals treat algae or weeds, please keep in mind the following:
- Treat your pond in sections. Treat only half the pond's surface at a time. If the weather is hot, only treat 1/4-1/3 of your pond, and wait 10-14 days between treatments.
- Once the weeds have browned & died, use a rake to remove as much dead material as possible. This prevents an accumulation of dead plant material and muck.
- Take a proactive approach to pond management. Use PondClear™, MuckAway™ and Pond Dye to keep your pond looking great. For more information, see our article on the Airmax® Ecosystem™
Ask an Expert
If you are unable to identify your pond weed(s) using our Weed ID Guide, follow this article to email us a photo.
Applied Biochemists Cutrine®-Plus Granular Algae ControlFast-Acting Granular Formula Great For Bottom Growing Algae & Chara No Water Use Restrictions Cutrine®-Plus Granular Algaecide has the same active ingredient as the liquid version, is fast-acting, plus works great on bottom forming algae,...Read More »$49.99–$99.99
Hydrothol® Granular Aquatic Algaecide & HerbicideFast-Acting Granular Formula Great For Bottom Growing Algae & Chara Control Weeds Surrounding Docks & Shorelines Hydrothol provides rapid-acting contact control for submerged weeds and algae. Hydrothol even works where there is moving water...Read More »$119.99