Hair and Thread Algae in Aquariums
Hair and thread algae form long green strands driven by excess light or a nutrient imbalance. They are controlled by manual removal, rebalancing and grazers.
Identification
Hair and thread algae appear as long, fine green strands that attach to plants, hardscape and equipment. They resemble wet hair when lifted out of the water and can form dense tangles. They are common in planted tanks and grow quickly under favourable conditions.
Causes
These algae are driven by an imbalance between light and nutrients. Excess light, an oversupply of nutrients such as iron, or conversely insufficient nutrients relative to a high light level all allow hair algae to take hold. As with other nuisance algae, the underlying problem is that conditions favour the algae over the plants.
How to remove it
- Twist large clumps out by hand or wind them around a toothbrush.
- Reduce lighting duration or intensity if light is excessive.
- Adjust fertilization: increase nutrients if plants are starved, or decrease iron dosing if it is too high.
- Perform water changes and improve overall plant health.
Animals that help
Several grazers consume hair and thread algae as supplementary control, including amano shrimp, Siamese algae eaters, mollies and Florida flagfish. They work best alongside manual removal and correcting the light and nutrient balance.
Restoring balance
Lasting control comes from getting light, nutrients and CO2 back into balance so plants grow vigorously and outcompete the algae. Adjust one factor at a time and allow two to three weeks to judge each change before adjusting further.
Prevention
- Keep the photoperiod and intensity matched to plant needs.
- Dose nutrients consistently and avoid overdosing iron.
- Maintain a strong mass of healthy plants.
- Remove strands promptly before they spread.