You are currently viewing April Algae Blooms are Off to an Early Start This Year

April Algae Blooms are Off to an Early Start This Year

With an early(ish) spring this year, we are getting quite a few inquiries about early-season algae issues. While mid-April is earlier than usual for significant algae issues on most ponds, the reason for the timing is explainable.

The relatively mild winter, with thinner than normal ice and little snow-cover allowed more sunlight to penetrate to the bottom of many ponds over the winter. Because of this, algae mats were able to form on the pond bottom even before the ice went out. Cold water temperatures help to moderate this growth, but it doesn’t stop if there is adequate sunlight.

Algae results from the combination of water, sunlight and nutrients. Therefore, reducing or eliminating any of those things from your pond will help reduce algae growth. Water obviously cannot be reduced, so that leaves us with sunlight and nutrients.


Using a pond dye helps “shade” the water, reducing sunlight penetration and reducing the energy available to grow algae and other plants. For this to be effective, you need to use the appropriate amount of dye for the volume of water that you have, usually expressed in acre-feet. To calculate the volume of your pond, you need to know the average water depth as well as the surface acreage.


Nitrogen and Phosphorus are the primary nutrients that stimulate algae and weed growth in a water body. These nutrients come from a number of sources, some avoidable and some not. A good first step in nutrient management is to think about what can be done to avoid nutrient introduction. Reducing nutrients like lawn fertilizer in run-off water can be an important thing. The next step is to reduce the nutrients that are already in the pond. Generally, this is accomplished with a combination of aeration and beneficial pond-cleaner bacteria.

The aeration circulates and oxygenates the water, the bacteria (which need oxygen) consume the nutrients and remove them from the pond. This combination works over time to reduce algae growth and keep it from getting out of hand.


You can use liquid algaecides to control algae that is floating on top of the water, or granular algaecides to control algae that is growing on the bottom of the pond.  Both materials are “contact herbicides” and work on the algae that is present at the time of the treatment. Neither material prevents algae growth in the future. Algaecides work (and work well) on the problem that you are looking at today, but repeat treatments will be required throughout the season if you don’t take preventative steps as well.

Keep in mind that some algae growth is normal and necessary to support the food web in your pond if you want to maintain a fishery. Pond management isn’t generally about eliminating all algae and plant growth from the pond, that’s what you do with a swimming pool. If you are managing a pond only for swimming, you can be more aggressive with algae management.

Taking the proper steps to aerate and use beneficial pond-cleaner bacteria in your pond as well as adding some water dye can help your pond stay clean and clear. If things are getting out of hand already, you may want to consider adding an algaecide treatment to your pond a little earlier than usual this year.

Whatever your algae challenges may be this spring, we are here to help. Give us a call or email for expert advice on how to manage your pond for the results you want.