When people start planning a custom aquarium, one of the first questions they ask is:

“What filtration do I actually need?”

The truth is, filtration is where most hobbyists overspend. Many stores push equipment that looks impressive, but doesn’t add real value or isn’t right for your specific tank.

This guide breaks down what’s truly essential, what’s optional, and what you can safely skip depending on your setup.

What Aquarium Filtration Actually Needs to Do

Every filtration system simple or advanced has the same three jobs:

1. Mechanical Filtration

Removes physical waste (fish poop, debris, uneaten food).

2. Biological Filtration

Holds beneficial bacteria that eliminate ammonia and nitrite.

3. Chemical Filtration (Optional)

Removes discoloration, odors, medications, and impurities.

That’s it.

Everything else is just different ways of doing these same jobs.

The 2 Filtration Systems That Work Best for Custom Aquariums

There are dozens of filters on the market, but only two systems make sense for custom tanks 40+ gallons

1. Sumps (Best for 90% of Custom Tanks)

Sumps are the gold standard for both freshwater and saltwater builds.

Why Sumps Are the Best Choice

• Hidden equipment → clean, rimless display
• Massive filtration capacity
• Easier maintenance
• More stable water volume
• Allows for customization (skimmer, media, refugium, etc.)

Who Should Choose a Sump

• Saltwater systems
• Reef tanks
• Planted aquariums
• Large freshwater tanks (90–400 gallons)

Who Doesn’t Need a Sump

• Nano tanks under 40 gallons
• Simple freshwater setups with small bioload

2. Canister Filters (Best for Smaller or Budget Builds)

Canisters are compact and powerful good for small and medium freshwater tanks.

Pros

• Quiet
• Good mechanical + biological filtration
• Easy to hide in cabinetry
• Budget-friendly compared to sump systems

Cons

• Not ideal for large or saltwater builds
• Maintenance can be messy
• Less oxygenation than a sump

Who Should Choose a Canister

• Freshwater tanks under 100 gallons
• Community tanks
• Planted tanks that don’t need high oxygen turnover

Filtration Equipment You Don’t Actually Need

Many aquarium stores upsell equipment that most hobbyists simply don’t need.

Here’s what you can skip:

x UV Sterilizers

Useful for very specific cases (green water, parasites), but not required for 95% of tanks.

x Protein Skimmers on Freshwater Tanks

Completely unnecessary unless you’re running saltwater.

x Chemical Filtration 24/7

Carbon or Purigen can be helpful but they are not required constantly.

x Oversized Canisters “for safety”

Turning your tank into a washing machine doesn’t help.

x Complicated filter media stacks

Most bacteria live on one good bio media type. You don’t need 7 layers.

What You Do Need for a Healthy Custom Aquarium

✔ A reliable biological filter

Examples:

• Sump bio media
• Ceramic rings
• MarinePure
• Bio balls
• Matrix

✔ Easy access for maintenance

If it’s hard to clean, you won’t clean it and water quality suffers.

✔ Correct flow rate

General rule:

• Freshwater: 5× tank volume per hour
• Saltwater/Reef: 7–10× tank volume per hour

✔ A filtration system sized to your bioload

A heavily stocked tank needs more turnover.

A lightly stocked planted tank can run lean.

Examples: Choosing the Right Filtration for Different Tanks

Example 1: 120-Gallon Reef Tank

Best choice: Sump

• Protein skimmer
• Filter socks or rollers
• Bio media
• Return pump
• Optional refugium

Example 2: 75-Gallon Planted Community Tank

Best choice: Canister

• Good bio media
• Light mechanical filtration
• No chemical filtration needed unless water yellows

Example 3: 150-Gallon African Cichlid Tank

Best choice: Sump or large canister

• Strong mechanical filtration
• Lots of bio media
• No skimmer needed

Example 4: 20–40 Gallon Nano Tank

Best choice: AIO back chamber or small canister

• Sponge + bio media
• No sump required

When We Build Custom Tanks, Here’s What We Recommend

At Concept Aquariums, we design filtration around:

• Your tank size
• Your livestock
• Your maintenance habits
• Your budget
• Your long-term goals

Most of our customers choose a sump system because of the stability, ease of access, and long-term cost savings but we build around whatever makes the most sense for your setup.

Want Help Choosing Filtration for Your Custom Aquarium?

We’ll map out the ideal filtration based on your tank size, fish, and goals.

Contact us for a custom recommendation →