Dealing with Euglena in Your Dam: What it is, Why it’s Tough, and How to Treat it
Q. We seem to have a problem with what we believe is Euglena. It is red throughout the day and turns green in the evening. It is a light dusting on the dam and will blow to the edge from the wind.
ANSWER
Thank you for reaching out after spotting a vivid green bloom across the surface of your dam. After reviewing the photos, we identified this as Euglena. While Euglena isn’t one of the more common algae types, this can be treated with Coptrol™.
Why Is Euglena Tricky?
Euglena is part algae, part protozoan, which makes it a bit of a shape-shifter. It can photosynthesise like a plant when light is available, but it can also survive in darker, low-oxygen environments. Because of this adaptability, it’s especially resilient—particularly in shallow, nutrient-rich dams, where sunlight easily reaches the bottom and energy levels are high. This gives Euglena a constant boost and makes it harder to remove compared to other algae types.
Step 1: Treating the Bloom with Coptrol™
In your case, the dam holds approximately 160,000 litres of water. To treat this volume, we recommended applying between 1L and 3.5L of Coptrol, depending on how advanced the bloom is.
If you’re unsure how severe your bloom is, a general guide is:
- Light bloom: 1L per 160,000L
- Moderate bloom: 2L per 160,000L
- Heavy bloom: 3–3.5L per 160,000L
Coptrol works by targeting the algal cells and breaking them down over several days
Step 2: Sinking the Dead Algae with a Flocculant
After the algae starts to die off, you may notice a layer of scum or fine particles floating across the surface. This is where a flocculant comes in.
We recommend using Aquatic Clear Dam—a flocculant that binds to particles in the water, including dead algae, and sinks them to the bottom. This not only clears up the water quickly but also helps reduce the available nutrients floating in the water column.
A single 5L container of Clear Dam will treat up to 250,000L, making it more than enough for a 160,000L dam. Application is simple—just spray it evenly over the surface.
Step 3: Long-Term Prevention with Aquatic Blue
Once the dam is cleared up, it’s time to think about keeping it that way.
We always suggest applying Aquatic Blue—a concentrated pond dye that limits sunlight penetration and helps suppress future algal growth. Because algae rely on sunlight to photosynthesise, reducing UV exposure is a highly effective way to slow down or prevent blooms from returning.
For a dam of 160,000L, you’ll only need about half a litre. Aquatic Blue lasts between 4 to 6 months, and the best times to apply are at the start of winter and again in spring. This gives you coverage through both the cooler months (when water clarity is naturally higher) and the warmer months (when blooms tend to return).
Another benefit, Aquatic Blue also gives your dam a deep, natural blue tone.
While Euglena can be more resilient than typical algae, it’s still manageable with the right approach. By treating it with Coptrol, sinking it out of the water column with a flocculant, and following up with a UV-reducing dye like Aquatic Blue, you can restore your dam to a clean, healthy state—and keep it that way long-term.
