💧 Cloudy or green water in freshwater aquariums – causes, solutions & natural remedies

🌊 When the water is suddenly no longer clear…

A newly set up aquarium with crystal-clear water is every aquarist's dream. But suddenly it becomes milky, greenish, or opaque – a problem that almost everyone experiences sooner or later. 🤔

Cloudy water doesn't just look unsightly; it can also indicate imbalances or overloading in your aquarium. The good news: with a little knowledge and the right measures, you can quickly get your water crystal clear again. 💧

🔍 Typical causes of cloudy or green water

Not all murky water is the same. Depending on its appearance, the causes can usually be identified just by looking at it:

☁️ Milky cloudiness (bacterial bloom)

  • Often found in newly set up aquariums

  • It arises from the explosive growth of bacteria.

  • Usually harmless and disappears on its own after 1-2 weeks.

🌿 Green water (algal bloom)

  • Fine suspended algae turn the water green.

  • Often caused by too much light and nutrients

🪱 Turbidity caused by suspended particles

  • Particles or soil substrate that are not fully filtered

  • Often occurs after interior work or fish activity

🧪 Main causes at a glance

  1. 🍽️ Overfeeding – too much leftover food → nutrient surplus

  2. 🧪 Too many nutrients – nitrate & phosphate promote algae growth

  3. 🌞 Too much light or too long – promotes suspended algae

  4. 🪵 Insufficient filter performance – suspended particles are not removed

  5. 🌱 Lack of competing plants – excess nutrients are left for algae.

✅ Step-by-step: How to get clear water again

🪣 1. Perform a partial water change

Perform a 30–50% water change. This will dilute nutrients and remove some of the suspended algae or bacteria.

🍤 2. Reduce the amount of food

Feed only as much as your fish and invertebrates can eat in 1-2 minutes. Excess food is one of the most common causes of algae blooms and cloudiness.

💡 3. Adjust light duration and intensity

Reduce the lighting to 6-8 hours daily. Too much light combined with nutrients is the perfect trigger for green water.

🌿 4. Use plants as competition

Fast-growing plants like hornwort or waterweed deprive algae of nutrients and ensure stable water in the long term.

🐌 5. Use natural helpers

Invertebrates can also be a valuable help when the water is cloudy. Snails and shrimp ingest organic matter and help keep it clean.

  • 🦐 Amano shrimp – remove the finest particles and leftover food

  • 🐌 Tower snails – burrow through the soil and prevent rot

  • 🐌 Ramshorn snails – remove algae and biofilms

👉 You can find these and other useful invertebrates in our shop – they support your aquarium naturally and without chemicals.

🧪 6. Regular care & check-up

  • Regularly check nitrate and phosphate levels with water tests.

  • Clean filter material as needed, without removing all bacteria.

  • Remove dead plant matter immediately.

🧠 Prevention: How to keep your water permanently clear

  • 💧 Weekly water changes (20–30%)

  • 🍤 Customized feeding

  • 🌞 Check lighting duration

  • 🌿 Use fast-growing plants

  • 🦐 Keeping beneficial invertebrates permanently in the terrarium

✅ Conclusion: Cloudy water is no reason to panic

Milky or greenish cloudiness is unsightly, but easy to manage . There's usually a simple cause – and with targeted measures like water changes, adjusting your feeding, and using natural remedies, you can quickly get your aquarium clear and healthy again. 🌿💧

👉 In our shop you will find a selection of invertebrates and accessories that will keep your water permanently clean and biologically stabilize your aquarium.

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