Black Sludge in Your Diesel Tank?

Your fuel is contaminated — and your equipment is at risk.
See How to Fix It

What You’re Seeing in Your Fuel

If your diesel sample looks like it contains black flakes, sludge, or debris — you are dealing with fuel contamination.

This is typically caused by:

  • Microbial growth (diesel bacteria & fungus)
  • Water intrusion in the tank
  • Fuel oxidation and breakdown

This is NOT normal diesel fuel.

How to confirm (quick field checks)

  1. Smear test
    • Rub particles between fingers (use gloves)
    • Slimy/stringy → microbes
    • Dry/gritty → dirt/rust
    • Rubbery/Spongy → fuel hose deterioration from the inside
  2. Water check
    • Pull bottom sample
    • Look for haze or separation
  3. DS-1 Microbe test kit
    • Confirms active microbial growth

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What Happens If You Ignore It

  • Clogged filters and unexpected shutdowns
  • Injector damage and costly repairs
  • Generator failure during emergencies
  • Accelerated tank corrosion

Most failures happen when the system is finally needed.

How Bad Is Your Contamination?

If your fuel contains visible particles like this, contamination is already advanced.

  • Light haze → early stage
  • Visible particles → moderate contamination
  • Black sludge/clumps → severe microbial growth

Your sample indicates a moderate to severe condition.

The Correct Way to Fix Diesel Contamination

Quick fixes like additives alone do NOT solve this problem.

Step 1: Remove Water

Microbes cannot survive without water — this is critical.

Step 2: Remove Solids

Use high-efficiency filtration or centrifuge systems to remove sludge and debris.

Step 3: Kill Remaining Microbes

Apply biocide AFTER cleaning — not before.

Step 4: Maintain Clean Fuel

Install continuous polishing or routine maintenance.

Why Dieselcraft Systems Work

  • Removes water, sludge, and fine particles simultaneously
  • No disposable filters required
  • Continuous cleaning prevents future contamination
  • Trusted for generators, fleets, and bulk fuel storage

Fix the root problem — not just the symptoms.

Stop Fuel Problems Before They Shut You Down

Get expert help diagnosing and fixing your diesel contamination today.
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Frequently Asked Questions

Is this diesel algae?

Yes — commonly called diesel bug, it is microbial contamination.

Will additives fix this?

No. Additives alone cannot remove sludge or solids.

Water caused the problem. You must get the water out and filter the fuel.

Do I need fuel polishing?

If contamination is visible, polishing / cleaning is required.

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