🌿 Algae in freshwater aquariums – causes, solutions and natural remedies

🧪 When the aquarium suddenly turns green…

Almost every aquarium owner knows the problem: Suddenly, green thread algae grow on plants, brown deposits cover decorations, and annoying green spots appear on the glass. 😬
Although algae are a natural part of every aquarium, if they become excessive, they not only look unsightly but can also harm plants, animals and the biological balance.

The good news: With the right knowledge, a few simple steps, and natural aids, you can get algae growth back under control. 🪸

🔍 Typical types of algae and how to identify them

Before you take action, you should know which type of algae you're dealing with. Not all of them react to the same solution.

🌿 Thread algae

  • Long, green, soft threads

  • They adhere to plants, stones, or roots.

  • They often occur in cases of nutrient imbalance .

🪸 Spot algae

  • Small, hard, green dots on discs or leaves

  • Indication of too much light or too much phosphate

🟤 Diatoms

  • Brown, slimy coating on decorations and plants

  • Common in new aquariums or with excess silicate

🪶 Suspended algae (green water)

  • The water turns green and cloudy.

  • Mostly due to too much light and too many nutrients.

📉 Causes of excessive algae growth

Algae don't just disappear by chance. They are a sign that something is out of balance in the aquarium. Common causes:

  1. 💡 Too much light – excessively long lighting times or too strong light

  2. 🍽️ Too many nutrients – especially nitrate and phosphate from leftover food or plant debris

  3. 🌿 Too few plants – algae use up excess nutrients when plants don't consume them.

  4. 🧪 Nutrient imbalance – e.g., high nitrate, low phosphate or vice versa

  5. 🪵 Overfeeding & overstocking – more waste = more algae food

✅ Step-by-step: How to get rid of algae

🪣 1. Analyze the causes and check the water parameters

Regularly measure nitrate, phosphate, and pH levels. High levels are a clear sign of excess nutrients. Target values:

  • Nitrate: 10–25 mg/l

  • Phosphate: < 0.5 mg/l

💡 2. Adjust lighting time

Many aquariums are simply overlit . For most tanks, 6-8 hours of light per day is perfectly sufficient.
👉 Tip: A 1-2 hour break from lighting at midday can help slow down algae growth.

🌿 3. Use fast-growing plants

Algae compete for nutrients. The more plants you use, the less "food" is left for algae.
Particularly helpful: Elodea (waterweed), Ceratophyllum (hornwort), Hygrophila or Vallisneria.

🧼 4. Reduce the amount of food & change the water regularly

Feed only as much as the animals can eat in 1-2 minutes. Excess food is the main reason for rising nitrate levels.
👉 20–30% water changes per week keep nutrient levels low.

🐌 5. Use natural algae eaters

This is where our little helpers come in: Invertebrates are true algae eaters and help you keep your aquarium permanently clean:

  • 🐌 Racing snails and tower cap snails – against growth and spot algae

  • 🦐 Amano shrimp – true filamentous algae specialists

  • 🐌 Ramshorn snails – tireless glass cleaners

👉 In our shop you will find a wide selection of beneficial snails and shrimp that naturally combat algae and keep your aquarium clean – completely without chemicals.

🪸 6. Optimize plant care and fertilization

A common mistake: too little or the wrong kind of fertilizer. Plants need all macro- and micronutrients to grow quickly.
If one is missing, they cannot utilize nutrients – and algae take over.

👉 Tip: Use a high-quality liquid fertilizer and ensure a balanced supply of nutrients.

💡 Prevention: How to permanently prevent algae

  • 🌱 Use enough fast-growing plants

  • 💡 Check lighting regularly

  • 🍤 Feed only as much as necessary

  • 💧 Perform regular water changes

  • 🐌 Keeping natural algae eaters permanently in the aquarium

🧠 Conclusion: Algae are no reason to panic

Algae are a natural part of any aquarium – but if they get out of control, it's a sign of an imbalance. With a combination of proper care, appropriate lighting, healthy plants, and natural helpers, you can quickly get them under control again.

👉 Check out our shop now and discover our selection of algae eaters, shrimp, snails and accessories to keep your aquarium clean and healthy for the long term 🌿🐌

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