1. Internal Filter

• Placed inside the aquarium, usually attached to the glass.

• Provides mechanical and biological filtration; some models also include chemical filtration.

• Operates quietly and is easy to set up.

• Suitable for small to medium aquariums (30–100 liters).

• Easy to clean but can affect the tank’s aesthetics and take up space inside.

1. External Filter

• Placed outside the aquarium, usually under the stand.

• Provides stronger biological and chemical filtration thanks to its large filter media capacity.

• Suitable for large aquariums (over 100 liters).

• Ensures excellent water circulation and doesn’t take up space inside the tank.

• More expensive, with a more complex setup and cleaning process.

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1. Hang-On-Back (Waterfall) Filter

• Hangs on the back glass of the aquarium and operates externally.

• Creates a waterfall effect at the surface, providing both filtration and aeration.

• Ideal for medium-sized aquariums (40–150 liters).

• Versatile when quiet models are chosen.

• If not properly maintained, it may cause leaks or noise.

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1. Comparison of Filter Types

• Internal Filter: Affordable, easy setup, minimal adjustments required, but takes up tank space.

• External Filter: Highest performance and clean look, but costly and more complex to maintain.

• Hang-On-Back Filter: Aesthetic, mid-level performance, easy external installation, may generate some noise.

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1. Which Filter Is Suitable for Whom?

• For beginners with small tanks, an internal filter is ideal.

• For experienced users and large aquariums, an external filter is recommended.

• For planted tanks, medium-sized tanks, and those prioritizing aesthetics, a hang-on-back filter is a good option.

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Conclusion
Choosing an aquarium filter depends on the tank’s size, setup, and the user’s experience. A well-functioning filter is vital for fish health and stable water conditions. By selecting the right filter, you’ll face fewer issues in the long run and enjoy a more satisfying aquarium experience.