Aquarium filters - how to choose?

🔬 WHAT IS AN AQUARIUM FILTER AND WHAT IS IT USED FOR?

An aquarium filter is a device that:

cleans water mechanically,

breaks down waste biologically,

treats water chemically,

provides flow and oxygenation.

📌 Filter = lungs + liver + kidneys of the aquarium

⚙️ HOW DOES AN AQUARIUM FILTER WORK?

1️⃣ Mechanical filtration

captures impurities (food residues, feces)

uses foam, cotton wool

2️⃣ Biological filtration

colonies of nitrifying bacteria

decomposition of ammonia → nitrites → nitrates

3️⃣ Chemical filtration

activated carbon

zeolite

phosphate absorbents

🧠 "NATURE" OF FILTERS (IMAGE)

🧘 stable and durable

⚠️ sensitive to neglect

🐌 they work continuously

❌ they do not forgive failures

🏠 REQUIREMENTS OF FILTER OPERATION
💧 Water

must always flow

without air, colonies die

⚡ Electricity

continuous operation

outage over 2–4 hours = risk

🧼 Maintenance

gentle cleaning in aquarium water

never under the tap

🧱 TYPES OF AQUARIUM FILTERS
🧲 1️⃣ Internal filters

✔️ cheap

✔️ simple
❌ less power

🛢️ 2️⃣ External filters (canister)

✔️ high biological capacity

✔️ quiet operation
❌ higher price

🫧 3️⃣ Air (foam)

✔️ ideal for fry

✔️ simple
❌ weak mechanical filtration

🧱 4️⃣ Bottom filters

✔️ biological filtration
❌ outdated solution

🌊 5️⃣ Hanging filters (HOB)

✔️ easy installation
❌ less widespread in Europe

🧪 FILTER MEDIA

foam

ceramics

bio-balls

activated carbon

peat

🩺 IMPACT ON FISH HEALTH
POSITIVE

✔️ low ammonia
✔️ stable water
✔️ fewer diseases

NEGATIVE (with a broken filter)

❌ poisoning
❌ stress
❌ death

🦠 "DISEASES" OF FILTER

clogging

bacteria decay

aeration

reduced flow

➡️ result: ecosystem collapse

⚖️ ADVANTAGES AND DISADVANTAGES OF FILTER

👍 ADVANTAGES

✅ clean water

✅ biological stability

✅ healthy fish

👎 DISADVANTAGES

❌ energy consumption
❌ maintenance
❌ noise of cheap models

🛒 HOW TO CHOOSE THE RIGHT FILTER?

✔️ aquarium volume
✔️ type of fish
✔️ plants
✔️ noise
✔️ budget

📌 rule: a stronger filter is better than a weaker one

🧭 PRACTICAL TIPS

clean the filter gradually

never wash all the media at once

have spare parts on hand

remove the carbon when treating

📌 SUMMARY

The filter is the heart of the aquarium.
Without it, the water rots, the fish suffer and the system collapses.
A properly selected and maintained filter:

maintains balance,

protects fish,

simplifies maintenance.