Fuel Filter Plugging – Microbial Growth and Issues

What’s happening?

In Spring, we need to be aware of substantial temperature swings that could increase moisture-related issues in fuel tanks. Tank maintenance programs using a combination of fuel cleaning, tank maintenance, and biocide products are instrumental in solving moisture-related issues (caused by microbial growth) and preventing the recurrence of future problems.

When temperatures change, warm air loses its ability to hold as much water vapor. This results in condensation and causes water accumulation. Freezing and thawing temperatures also lead to water in storage tanks (i.e. water can seep into cracks and crevices and expand as it freezes, leading to openings that can let water in). As end-users get moving this Spring, they should pay extra attention to moisture levels in tanks. When care is needed, additional levels of moisture control will help to suspend and remove moisture.


It is good to have a plan in place to deal with potential moisture-related issues and prevent future occurrences.

What is microbial growth? How can it be mediated?

Microbial growth in fuel

Microbial growth (commonly referred to as bugs or algae) goes hand in hand with high moisture levels. When conditions are right for growth to occur, these microorganisms thrive and can cause a wide range of issues in fuel storage tanks and vehicles.

These organisms use fuel as a food source, but they also need water to become active. As water saturates out of fuel and settles to the bottom, it turns into a breeding ground for microbial growth to flourish.

Proper treatment with biocides and tank cleaning chemicals can help ensure that customers’ tanks are clear of bacteria-related issues.

Read more here about microbial contamination.

Tell-Tale Signs of Fuel Filter Plugging

plugged fuel filter

A common indicator for microbial issues is a slowed fuel flow caused by filter plugging.

Clogged filters often become coated with and contain dark slimy substances in the filter media.

Many microbial growth forms also cause damaging corrosion causing a host of other problems. By far, the most common shared element between all types of microbial growth is the presence of a water bottom in the tank where the growth is occurring.

No matter how it appears, microbial growth can be very frustrating to end-users.

Tank Maintenance Programs

Tank maintenance programs are great for keeping microbial growth at bay and ensuring that fuel storage tanks are in good shape.

Typical tank maintenance programs include fuel cleaning additives. These additives can help maintain tank cleanliness and housekeeping operations ensuring that tanks do not allow in water and moisture. A tank maintenance program can also offer fuel testing to better understand your fuel.

Recommendations for Controlling Microbial Growth

Checklist for End-Users

Checklist for Drivers