Fine Slime, is it Algae or Sediment?
Q. We are having trouble with our self-cleaning filter on one of our dams, it seems to be blocking up with a fine slime.
ANSWER
How to Treat Fine Slime in Your Dam
If you’ve noticed a fine slime floating or suspended in your dam, the first step is figuring out what it actually is. While it might all look the same at first glance, this slime is usually caused by either sediment or algae — and each requires a different treatment.
Step 1: Identify the Slime
Grab a small amount of the slime and rub it gently between your fingers.
If it feels gritty, like sand
This indicates sediment — fine soil particles that are staying suspended in the water rather than settling to the bottom.
If it feels slippery or slimy
Especially if it’s green, brown, or black and has a slight odour, you’re dealing with algae.
Step 2: Treat Accordingly
For Sediment (Gritty Feel)
Use a flocculent such as Aquatic Clear Dam.
Flocculents work by binding fine particles together so they become heavy enough to settle to the bottom.
Application rate:
➡️ 5L per 250,000 litres of water – dilute 1 part product to 20 parts clean water.
This is the best solution when the issue is purely sediment-based.
For Algae (Slimy Feel)
Start with an algaecide, such as Coptrol, to kill the algae causing the problem.
Application rate:
➡️ 4.2L – 8.4L per 1,000 square meters of water surface area – dilute 1 part Coptrol to 10 to 20 part of clean water.
After treatment, wait 72 hours. Once the algae has died off, assess the water clarity. In some cases, the dead algae will settle naturally. If not, a follow-up application of a flocculent can help speed up the clearing process.
Do You Always Need Both Treatments?
In most cases, treating the algae alone is enough to clear the water. However, adding a flocculent after algae treatment can significantly improve results and reduce clearing time — especially in heavily affected dams.
If you’re unsure which treatment is right for your dam, identifying whether the slime is gritty or slimy is the simplest and most reliable place to start.
