The Complete Guide to Freshwater Aquarium Filtration

Filtration is what keeps freshwater aquarium water clean and stable over time, reducing dirt, odors, and risks to fish. This Animal Instinct guide provides a comprehensive explanation.

What is filtering?

In an aquarium, dirt doesn't disappear: it's retained and, more importantly, transformed. The filter works like a small purification system that operates on multiple levels.

• Filtration mechanical : stop visible particles (debris, uneaten food) using sponges/wool.
• Filtration organic : hosts beneficial bacteria that convert toxic substances (ammonia and nitrites) into nitrates, which are more manageable with water changes and plants.
• Filtration chemistry (only when needed): for example activated charcoal to remove drug residues or unwanted substances, it is not always “mandatory”.

The 2 most commonly used types of filters in freshwater

For most home aquariums, the practical choice often comes down to: internal filter or backpack filter. Both options are available in the Animal Instinct shop.

Internal filter: compact and immediate

The internal filter fits inside the tank: it's easy to install, especially suitable for small/medium aquariums and for those who want a simple product. Our catalog includes the SICCE Nano Micron , an internal solution available in several versions. We also offer the new Shark PRO filter, available in 3 different sizes.

Backpack filter (hang-on): convenient to handle

The backpack filter hangs on the edge of the aquarium, freeing up space in the tank and being easy to open and clean; it's often a popular choice for small aquariums, open tanks, or minimalist setups. At Animal Instinct, you'll find the SICCE Tidal , SICCE Aqua Filtra , Angel 380 backpack filter , Angel 500 PRO backpack filter, and the new Mega Filtra for large aquariums.

Which filter to choose (quick criteria)

The right choice depends on three factors: tank capacity, number of fish (organic load), and ease of maintenance. Generally, the more populated the tank, the more convenient it is to have adequate filter volume and flow rate.

• If you want a simple “plug & play” solution in small tanks: consider SICCE Nano Micron .
• If you want easy access and quick maintenance, especially in small or open tanks: look at backpack filters Angel 380 or Angel 500 PRO .
  
• If you want the complete solution we recommend the new Mega Filtra for large aquariums.

Furthermore, in a modern marine aquarium, the skimmer is one of the most important tools for keeping the water clean and low in nutrients, preventing the buildup of organic substances that can stress fish and corals. For tanks up to 150-300 liters, a compact and quiet solution is the Shark SKIMMER SICCE , a low-consumption internal skimmer designed specifically for easy integration into mini reefs and home aquariums. Thanks to its magnetic mount and slim design, it can be installed directly in the tank without a sump, offering efficient skimming even for beginners who want more stable system management.

How to Make Your Filter Work Well (Without Beginner Mistakes)

A filter performs best when coarse dirt is removed first and the biological component remains stable. This is why it's important not to "sterilize" the filter during cleaning, because beneficial bacteria live there.

• Clean the mechanical part when the flow drops, rinsing in water taken from the aquarium (not in chlorinated tap water).
• Don't change everything (sponges/materials) at once on the same day: make gradual changes so as not to destabilize the bacterial colony.
• Remember that the filter does not replace water changes: nitrates and other substances can also be managed with regular maintenance.

Frequently Asked Questions About Freshwater Aquarium Filtration

What filter capacity do you need? 4-10 times the tank volume/hour (e.g. 200 litres = 800-2000 l/h).
Internal or external filter? External for tanks over 100L.
Where to buy in Rome? Animal Instinct, Via di Monteverde 2i with free assistance.

Ready to optimize your aquarium? Visit Animal Instinct in Rome or buy online. Sign up for our newsletter for exclusive guides and discounts on filters! Have questions? Comment below or contact us.

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