Weed & Algae Identification

This page serves as a pathway to identify pond weeds and algae, learn about control options, find a treatment plan and purchase products to control the vegetation.

To effectively control aquatic vegetation it is critical to first know the type of weed or algae that you are dealing with, and then develop a management plan. This plan could consist of many things, including controlling incoming nutrients, stabilizing shorelines, installing aeration equipment, encouraging growth of beneficial aquatic vegetation, mechanical harvest, biological control and chemical control.

Identify the Aquatic Vegetation

Click on the category that best describes your problem for identification information and treatment options, including links to products:

Algae in Koi Ponds and Water Gardens
Algae in Lakes and Ponds

Algae is an aquatic vegetation that has no leaves or vascular system, but does have Chlorophyll to make it green. Examples are water that looks like “pea soup”, “stringy green stuff” and floating mats of green, brown and yellow vegetation. 


Floating Weeds or Weeds with Floating Leaves:

These are plants that either are not rooted to the bottom and float on the surface of the water, or plants that are rooted on the bottom and have leaves floating on the surface.


Emergent Aquatic Weeds:

These are plants rooted underwater with some of their leaves extending above the surface. Usually found in shallow water along the shoreline.

Submerged Aquatic Weeds:

Plants entirely underwater, except some with flowers extending above the surface. Usually found from 1 foot deep out to over 10 feet deep (depending on water clarity and species).

Still Not Sure?

Submit a Sample: If you are still unsure of the type of vegetation, go to this link to submit a sample.

Aquaplant, a Pond Manager Diagnostics Tool: This is another option to identify pond weeds and algae. Their photos are terrific, but if you are in the north, keep in mind that some of their suggested management techniques are geared towards the south.


Product Selection and Application

Product Selection Chart: Once you know what type of weed that you have, use this chart to pick a product that will help control it.

Product Restrictions Table: Check to see what, if any, kind of water use restrictions apply, if any, for this product.

Weed & Algae Control Products: Purchase products to control aquatic weeds & algae.

Koi Pond and Water Garden Algae Mngt Plan: This page give you treatment ideas for controlling algae problems in Koi Ponds and Water Gardens.

Pond and Lake Weed and Algae Mngt Plan: This page puts it all together and gives possible treatment programs for some of the most common types of weed and algae problems.


Other Important Information

If you use chemicals as part of your management plan, be sure to thoroughly read and follow the manufacturer`s label instructions, and apply them in a safe and proper way. Also, contact your local Department of Natural Resources, or similar State Agency, for information on local regulations and permits (if any). None of our products are restricted use pesticides. When used properly, these products are safe and effective. However, we can not sell many of these products to NJ, NY, MA, CT, AK, ID, HI, ME, NH, VT, RI, WA & CA because of restrictive state laws.