🦠 Cyanobacteria in the saltwater aquarium – this is how you finally get rid of the red plague!

🧪 What exactly are cyanobacteria?

Almost every saltwater aquarium owner encounters them at some point: slimy, reddish-brown coatings that spread like a carpet over sand, rocks, or corals. 😖 They are often mistaken for algae – but in reality, they are cyanobacteria , ancient microorganisms that exhibit characteristics of both bacteria and algae.

👉 In short: Cyanos are not true algae , but bacteria that perform photosynthesis – and they can quickly make life difficult for your aquarium.

🔎 How to reliably identify cyanobacteria

Cyanobacteria are easy to spot if you know what to look for:

  • 🌱 Color: reddish, brown, sometimes even greenish or black

  • 🫧 Texture: slimy, slippery, often easily removable

  • 🫧 Location: mostly on sand, stones or at the current edge

  • 💨 Bubble formation: small oxygen bubbles on the surface

💡 If you can peel off a slimy film when changing the water, you are very likely dealing with cyanobacteria.

🧬 Causes – why cyanobacteria develop

Cyanobacteria don't appear by chance – they are a sign of an imbalance . Common causes include:

  • 🍽️ Nutrient imbalance (too little nitrate or phosphate)

  • 💨 Weak current and “dead zones”

  • 💡 Too bright or wrong light

  • 🐟 Overfeeding and too much organic waste

  • 🧪 Too little competition from other microorganisms

🧹 Step-by-step: Naturally combat cyanobacteria

1. 🪸 Manual removal – the first step

  • Suction off the slimy deposits using a hose or pipette.

  • Repeat this step regularly to weaken the infestation.

👉 Tip: Never simply "stirre" the water, otherwise the bacteria will spread throughout the entire tank.

2. 🌬️ Optimize the flow

  • Cyanobacteria thrive in areas with low currents.

  • Position your pumps so that there is a slight movement of water everywhere.

3. 🧪 Balance nutrient levels

Keep your values ​​in the optimal range:

  • Nitrate: 2–10 mg/l

  • Phosphate: 0.02–0.08 mg/l

Too low levels promote cyanobacteria – targeted nutrient supplementation can help here.

🐌 4. Use natural cyanotoxin absorbers (effective & long-lasting)

One of the most effective and sustainable methods is the use of cyanoeaters – small helpers that specifically eat these deposits and keep your aquarium permanently clean.

✅ Typical cyano-eaters include, for example:

  • Snail species that graze on slimy coatings

  • Shrimp and hermit crabs that remove fine biofilms

  • Special cleaning crews that keep surfaces permanently clean

👉 In our shop you'll find practical complete sets with cyanobacteria that are perfectly coordinated. This allows you to quickly restore your aquarium's balance – without chemicals and with 100% natural support.

5. 🪵 Build competition

  • Macroalgae in the sump help to absorb excess nutrients.

  • Bacterial preparations strengthen the natural microfauna and suppress cyanobacteria in the long term.

6. ☀️ Check the lighting

  • Replace old light bulbs and reduce the lighting duration.

  • A short break from light (1-2 days) can significantly slow down cyanobacteria growth.

🚫 What you should avoid

❌ Using chemicals as a first measure only treats symptoms.
❌ Too many changes at once – better to do them step by step.
❌ Reducing nutrient levels to 0 often worsens the problem.

🧠 Prevention: How to keep cyanobacteria away permanently

  • 💧 Perform regular water changes

  • 🍤 Reduce feeding and make it more targeted

  • 🌬️ Adjust the flow regularly

  • 🪸 Build up competition through macroalgae and bacteria

  • 🐌 Keep cleaning teams with cyano-eaters permanently in the pool

✅ Conclusion: Patience + natural helpers = clean aquarium

Cyanobacteria are a nuisance, but a solvable problem. With a combination of improved conditions, targeted care, and natural cyanobacteria predators, you can get rid of them permanently – completely without chemicals or stress. 🌊


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