Coptrol 5-Step Method for Application

Coptrol Application

5-Step Method for Application of Coptrol Algaecide

We have developed a simple 5-step method at RCI to gauge the appropriate quantity of Coptrol for application.

1. Broadly identify the type of algae present

It is important to first determine if you have an algal bloom and not other forms of aquatic plants. Once algae is confirmed, it will present as either filamentous algae, free-floating algae or blue-green algae.

Use a stick to break the surface of the water where the algal bloom is occurring. Look at the underlying texture. Also, take a cup full of water and surface material, then let it rest.

  1. If the surface scum is composed of many small free-floating particles with roots – It is not algae.
  2. Stringy or hair-like scum – It is filamentous algae.
  3. If the water is a cloudy green  It is most likely free-floating algae.
  4. A water surface with an iridescent green or blue scum will most likely be toxic blue-green algae. This must be treated with caution. Call RCI 1800 257 193 (Toll Free) for assistance.

To further identify the algal species, you can take a photo and email it to and we will attempt to assist with identification. Alternatively, you can send your sample to an accredited water lab for full identification. Contact RCI if you need assistance finding an appropriate laboratory.

2. Calculate the surface area of water to be treated

As algae prefer sunlight and warmth to thrive, they generally only occur in the top layer of a body of water. Volume need only be calculated to a maximum depth of one metre.

Use Google Maps to find your property and the body of water you wish to treat. Use the “Measure Distance” tool to calculate surface area.

  1. Click on the “View larger map” link in the top left of the map window below.
  2. Find the body of water you want to measure.
    • Zoom into the map directly, or;
    • Use the search bar in the top left to enter the address of the property where the body of water exists.
  3. Once you have found the water body on the map, right-click with your mouse and use the “Measure Distance” tool.
  4. Using your cursor, click on the boundary of the water body. This will create an initial point.
  5. Continue clicking additional points around the edge of the water to best outline its shape.
    • Once you are at the last point, click once again on the initial point. This will close the loop and determine the area.
  6. The distance and area measurements will appear at the bottom of the map window. Read off the “Total Area” number and use this in the calculator below (or your own calculations).

3. Calculate the amount of Coptrol needed

Based upon the identification of algae type.

  • For fine or free-floating algae use 2mL per 1 x cubic metre (1000L) of water. This equates to 2L of Coptrol per 1000m3 of volume calculated.
  • For filamentous algae use 5mL per 1 x cubic metre (1000L) of water. This equates to 5L of Coptrol per 1000mof volume calculated.

4. Dilute the required amount of Coptrol

Coptrol should be diluted with water to between a 1:10 and 1:20 ratio.

  • For a dilution ratio of 1:10, add 1 Litre of Coptrol and 9 Litres of water.
  • For a dilution of ratio 1:20, add 1 Litre of Coptrol and 19 Litres of water.
Coptrol Calculation

Coptrol algaecide volume calculator

Use this calculator to determine the volume of Coptrol required for application. This calculator provides data for Steps 3 & 4 above.

Algae typically only grows in the warmer top layers of the water. Volume calculations for Coptrol treatment need to only consider the top 1 metre. 

Application Dilution

Please note: final dilution is a matter of personal preference. A dilution ratio anywhere between the two below is acceptable.

5. Apply

The best application method for Coptrol is spraying. Ideally, apply on a sunlit wind-free day soon after the algal bloom first appears.