Analysis of the results


Compare the bottle to the pictures found in the test kit daily; reading the final result after four days. With very heavy contaminated fuel a result can often be seen after just 1 day. With slightly contaminated fuel it can take longer, until a result becomes visible.


Evaluation of the results

Low contaminationzoom
No more than 2 spots: Low contamination

The level of contamination is not above that commonly found in clean diesel.
A new test in 4 – 8 weeks is recommendable to make sure that the value remains steady. Alternatively a prophylactic treatment with grotamar® 82* (25 ml per 100 l diesel) is recommended.

Moderate contaminationzoom
3-25 spots : Moderate contamination

Microbes are present above the numbers usually found in clean diesel.
A moderate dosage of grotamar® 82* (50 ml per 100 l diesel) is recommended to stop the contamination efficiently and fast.

Heavy contaminationzoom
More than 25 spots: Heavy contamination

Microbes are present in high numbers and you may experience fuel filter clogging or fuel injector problems.
Act immediately to help avoid potentially serious operational problems. With sludge in the tank system it is recommended to carry out a tank cleaning and to filter the contaminated fuel. The filtered fuel should be treated with a shock dosage of grotamar® 82* (100 ml per 100 l diesel) before returning into the cleaned tank. After completing these actions retest the system to ensure it has been successful.


  • If testing sludge which is dark or pigmented, be careful when observing results not to confuse particles of sludge with colonies of microbial growth.
  • It is the number of spots not their size which is important. Once a spot (= a colony) is counted do not count it again if it grows larger.
  • Some fuels may contain antioxidants which can produce a uniform pink or orange colour in the gel (usually within one day). This does not interfere with the growth of the microbes and the colonies should be counted ignoring the pink or orange colour.

* grotamar® 82 - the first biocide with a new protective formula for modern diesel fuels. Fast and effective against bacteria, yeasts and fungi. Available in 1l-bottle and 10l canister.

Use biocides safely. Always read the label and product information before use. Keep out of reach of children.

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Use biocides safely. Always read the label and product information before use.

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