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Filtration

Canister vs HOB Filter: Which is Better?

The great filter debate, settled. Here's when to choose canister, when to choose HOB, and what actually matters.

Last updated: December 2025 | 11 min read

Quick Answer

Under 40 gallons: HOB filters are usually fine. 40+ gallons: Canister filters become worth the investment.

Quick Comparison

Feature HOB Filter Canister Filter
Price $25-80 $80-300
Best Tank Size 5-55 gallons 30+ gallons
Filter Media Capacity Low-Medium High
Ease of Maintenance Very Easy Moderate
Noise Level Moderate Very Quiet
Setup Difficulty Easy Moderate
Visual Impact Visible on tank Hidden below

HOB Filters (Hang-On-Back)

Hang-on-back filters attach to the rim of your tank. Water is pulled up through an intake tube, passes through filter media, and cascades back into the tank.

Pros

  • ✓ Affordable (often under $40)
  • ✓ Easy to set up in minutes
  • ✓ Quick media changes
  • ✓ Good for small-medium tanks
  • ✓ Provides surface agitation
  • ✓ No priming required

Cons

  • ✗ Limited media capacity
  • ✗ Can be noisy (waterfall sound)
  • ✗ Visible on tank
  • ✗ Lower flow rates
  • ✗ Requires hood modifications
  • ✗ Water evaporation from waterfall

Best HOB Filters

AquaClear 50

20-50 gallon tanks | Customizable media | Lifetime warranty

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Seachem Tidal 55

Up to 55 gallons | Surface skimmer | Self-priming

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Canister Filters

Canister filters sit below or beside the tank. They use hoses to draw water out, pass it through multiple media trays, and return it via a spray bar or outlet. Much larger filter volume than HOBs.

Pros

  • ✓ Huge media capacity
  • ✓ Very quiet operation
  • ✓ Hidden from view
  • ✓ Higher flow rates
  • ✓ Flexible outlet options
  • ✓ Less frequent maintenance
  • ✓ Can add inline heater/UV

Cons

  • ✗ Expensive ($80-300+)
  • ✗ Complex setup
  • ✗ Requires priming
  • ✗ Potential leak points
  • ✗ Maintenance is messier
  • ✗ Takes up cabinet space

Best Canister Filters

Fluval 307

40-70 gallons | 303 GPH | AquaStop valves

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Fluval FX4

Up to 250 gallons | 700 GPH | Self-priming

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Eheim Classic 350

Up to 93 gallons | 163 GPH | Legendary reliability

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When to Choose HOB

An HOB filter is the right choice when:

✓

Tank is under 40 gallons - HOBs handle smaller tanks perfectly well

✓

Budget is limited - A quality HOB costs $30-60 vs $100+ for canisters

✓

You're a beginner - Simpler setup, easier maintenance learning curve

✓

No stand/cabinet - HOBs don't need under-tank space

✓

Surface agitation is needed - Good for fish that like oxygenated water

When to Choose Canister

A canister filter is worth the investment when:

✓

Tank is 40+ gallons - Canisters shine with larger water volumes

✓

Heavy bioload - Messy fish, high stocking, or lots of food

✓

Planted tank - Better CO2 retention, lily pipe options

✓

Clean aesthetic matters - No visible equipment on tank rim

✓

Want quiet operation - Canisters are nearly silent

✓

Less frequent maintenance - Clean every 3-6 months vs monthly

Filter Media Comparison

The amount and type of filter media is where canisters really win:

Typical HOB Media

  • • 1-2 cartridges/sponges
  • • Small amount of ceramic media
  • • Maybe carbon if there's room
  • • Total volume: 0.2-0.5 liters

Typical Canister Media

  • • Coarse sponge/filter floss
  • • Multiple trays of bio media
  • • Carbon, Purigen, or chemical media
  • • Fine polishing pads
  • • Total volume: 2-6+ liters

More media = more beneficial bacteria = more stable water chemistry = healthier fish.

Maintenance Comparison

HOB Maintenance (Monthly)

  1. 1. Turn off filter
  2. 2. Remove cartridge/sponge
  3. 3. Rinse in old tank water
  4. 4. Replace if worn out
  5. 5. Plug back in

Time: 5-10 minutes

Canister Maintenance (Every 3-6 months)

  1. 1. Close intake/output valves
  2. 2. Disconnect hoses
  3. 3. Carry canister to sink
  4. 4. Open canister (fight with clips)
  5. 5. Remove media trays
  6. 6. Rinse each tray in old tank water
  7. 7. Clean impeller and housing
  8. 8. Reassemble and prime
  9. 9. Check for leaks

Time: 30-60 minutes

Reality check: Canister maintenance is messier and more involved, but you do it much less often. The total time investment is similar.

Can You Use Both?

Yes! Many aquarists run both types together:

Why Combine Filters

  • • Redundancy if one fails
  • • More total filtration capacity
  • • HOB for mechanical, canister for biological
  • • Surface agitation + spray bar

Common combo: Fluval 307 canister + AquaClear 30 HOB on a 55 gallon tank. Overkill? Maybe. Crystal clear water? Definitely.

Calculate Required Filter Flow

Use our free calculator to determine the minimum GPH (gallons per hour) your tank needs.

Open Filter Calculator

Bottom Line

For tanks under 40 gallons:

A quality HOB filter (AquaClear, Seachem Tidal) is perfect. Save your money for fish and plants.

For tanks 40-75 gallons:

Either works. Canister if you want less visible equipment and less frequent maintenance. HOB if budget is tight.

For tanks 75+ gallons:

Canister is almost always better. The capacity difference matters at this scale.

The best filter is the one you'll actually maintain. If canister maintenance sounds intimidating, stick with HOBs. Consistency beats capacity.