Fuel Additives

bug1 smalldipslideSepar UK sells three varieties of fuel treatments aswell as microbial testing dipslides. Professional Fuel Testing is also available through our partner company, WASP PFS Ltd.




Bacterial infection is a major issue in fuel. There are hundreds of various bacterial infections, the two most common being “Cladosporium Resinae” (clad) and “Pseudomonas aeruginosa”.

These yeast and fungal infections cannot germinate in the fuel itself, but require the right temperature (10-40 degrees centigrade) a food source (the fuel’s hydrocarbons) and water to live. Bacterial infection most often looks like black or dark brown ‘waxy sludge’. This is often found in fuel tanks, pipes and filters. The by-product waste will then cause damage to engines.


Which treatment do I need?

This will depend on the following:-

  • the type of fuel (diesel, jet fuel etc)
  • where it is being used (on a boat, aircraft etc)
  • whether you need a biocide or biocide including improvement catalyst.

Kathon and BioKem are high performance antimicrobial agents developed to combat problems of microbial contamination and spoilage in hydrocarbon fuels. FT RED fuel treatment and improvement catalyst eliminates any fungal growth and bacterial build up, improves the fuels combustibility, cleans injectors and fuel system while improving power output.

The below table gives a good indication of which product is suitable for varying needs. If you are still unsure, please do not hesitate to This email address is being protected from spambots. You need JavaScript enabled to view it..

biocide table


Kathon FP 1.5 is a patented high performance antimicrobial agent developed specifically to combat problems of microbial contamination and spoilage in hydrocarbon fuels.


More Info




WASP Biokem SP15

WASP Biokem SP15 is a fuel micro-biocide for treatment of Cladosporium Resinae and Pseudomonas aeruginosa (the fuel bug).

More Info





WASP FTR (Fuel Treatment Red)

FTR medium

FT RED is a highly concentrated mixture of carefully formulated additives and solvents designed to easily mix with gas oils, diesel and fuel oils used for marine pleasure, ocean-going vessels, road haulage fleets, mechanical plant and agricultural units.

More Info




Fuel Testing Dip Slides for Microbial Infection

dipslidesThe Micro Dip Slides are easy to use and test for bacteria, yeast and moulds. 


More Info






On Site Fuel Testing

A comprehensive laboratory test carried out on your behalf by WASP PFS Ltd is by far the most accurate and sensible. We offer a full ISO4406 reading, percentage figures for composite parts of your fuel, as well as water content, sulphur levels, infection, etc. Our laboratory testing service then offers you a full written report, analysing your fuel and making recommendations based on your results. WASP PFS Ltd offer a comprehensive fuel testing service.






Microbial Dipslides

Testing Fuel for Infection

fuel bugStored fuel is at risk of infection such as bacteria, which can quickly multiple and if left untreated, can lead to failure of backup systems which could be disastrous in an emergency situation.

Water can form in any fuel tank, typically from condensation, poor ventilation or water ingress (especially common in marine vessels). Water, while a contamination itself, is the main cause of formation of all other forms of contaminations, such as bacteria, yeast and moulds.

Infections then quickly multiply and can lead to blocked fuel filters, damaged injectors, engine failure and can be potentially life threatening if back up power supplies fail.

The Solution

dipslideWe therefore recommend fuel is checked regularly for signs of contamination so any infection can be treated early on.

A simple dip slide test can give results within 1 – 5 days, allowing you to treat the contamination appropriately before it takes over.





 Quick, Simple and cost effective testing.

The Micro Dip Slides are easy to use and test for bacteria, yeast and moulds. 

Find out more about types of fuel contaminates.

The dip slide is held within a container which keeps the agar clean before and during processing. An instruction sheet and a growth chart are also included.For most accurate results, we recommend using an incubator to keep the sample at a consistent temperature of between 30 and 35 Degrees Centigrade. Available to buy in units of 1 or in a pack of 10.

Treating an infection

We highly recommend treating any bacterial infection as early as possible with WASP® BIOKEM SP15 to prevent further spreading of the bacteria. WASP® BIOKEM SP15 can be used to prevent further spreading of bacteria even with very heavy growth, but please note, it will not remove the residue already there. To remove existing residue, a fuel filtering system should be used. More Detailed Testing If you would like professional and detailed fuel testing, please contact us to discuss having fuel samples taken and sent to our lab for analysis. Preventative measures With the introduction of BioDiesel, the risk of contamination from bacteria is even higher. Bio-fuel is hygroscopic and attracts water, the cause of all microbial growth. We recommend regularly treating your fuel with WASP® BIOKEM SP15 as a preventative measure to avoid microbial growth. For more information on WASP® BIOKEM SP15 and to buy online, click here.

Dip slide UK pricing for Fuel Bug Dip Slide Tests

Please note, at this time we can only sell to UK mainland.




Fuel micro-biocide

For treatment of Cladosporium Resinae and Pseudomonas aeruginosa

(fuel bug)

Bacterial infections in fuel lead Biomass sludge to form, causing filters to clog and tank pitting. The knock on impact is systems stalling and if left untreated, the result is often permanent damage to fuel systems, as well as fuel being unusable. Replacing systems and fuel is then obviously a costly event which could have been avoided.


Did you know we sell Biokem online? visit our webshop (WASP PFS Ltd) by clicking here


What is Biokem?

WASP® BIOKEM SP15 is a concentrated effective biocide/fungicide designed for all fuel oils. Rapidly destroys micro-organisms and provides long term protection against further infection.

  • Effective at high dilution
  • Nitrite free
  • Universal application
  • Good material compatibility
  • Long Lasting
  • Supports anti-corrosive properties
  • Low toxicity
  • Boosts pH levels


How do I know I have a bacterial infection in my fuel?

bacteria on element smallYou will probably first notice you have a bacterial infection in your fuel when you see foreign matter floating on top or mixed in with the fuel.

Your boat or equipment using the fuel may not be running efficiently.

There are hundreds of various forms of bacterial infection which can live and multiple in fuel and can be all different forms, sizes, shapes and colours, from an earthy brown to luminous green.

 Does it work?

The effectiveness of WASP® BIOKEM SP15 has been proven over a number of years and it has extensive approvals endorsing its use in a wide range of fuel types.

It combines exceptional activity with broad spectrum performance, consequently it is effective at very low use levels against all commonly occurring fuel contaminates (bacteria, fungi and yeast). WASP® BIOKEM SP15 is a high performance antimicrobial agent developed specifically to combat problems of microbial contamination and spoilage in hydrocarbon fuels.

In 2011 it was entered into two magazine group tests, the results speak for themselves.

WASP biokem award 2 small WASP biokem award 1 small

Can I use WASP® BIOKEM SP15 to prevent a bacterial infection?

Yes, and we suggest doing so to avoid the costly expense of finding out about the infection when it is too late to be treated resulting in the need to replace storage equipment and your stored fuel.

Prevention is better than cure!

Do I need to remove the bacteria already there?

fuel sample bottles smallWASP® BIOKEM SP15 will kill live bacteria but to remove it completely, you will need to filter out the bacteria which is already in your fuel. It is worth noting other similar products claim to remove existing infections. While the majority of similar products may break down the infection (including BIOKEM), and prevent further infection, none will completely remove the matter already there. If you intend to use BIOKEM for a boat, it may already have a filter which can be run to clean out the matter.

If you would like more information on a filter system, please contact Separ on 01923 276 007 or email This email address is being protected from spambots. You need JavaScript enabled to view it..


  What quantity options are available?

  • 5kg (5 lit approx) bottles
  • 250ml bottles
  • 50ml bottles

What is the recommended dosage?

WASP® BIOKEM SP15 should be dosed as follows (based on the 250ml bottle size)

(dose ratio)
5L bottle treats
250ml bottle treats
50ml bottle treats
50000 litres of fuel
2500 litres of fuel
500 litres of fuel
Moderate contamination
25000 litres of fuel 
1250 litres of fuel
250 litres of fuel
Heavy contamination
15000 litres of fuel
750 litres of fuel 
150 litres of fuel


Treat as per table above and re-treat periodically at 5000:1 to 10000:1 to control re-infection. Best results are obtained if the system can be re-circulated to fully disperse the Biocide. When dosing with WASP® BIOKEM SP15, ALWAYS mix the required dose with a greater quantity of fuel BEFORE adding to the fuel tank. This ensures a quick and efficient dilution with the infected fuel. For bio-diesel we recommend double-dosing, so a 250ml bottle is enough to treat 375 litres of fuel with heavy contamination (1500:1).

Download a PDF of BIOKEM Information

Place an order OR Find out more

Contact Separ on 01923 276 007 or This email address is being protected from spambots. You need JavaScript enabled to view it.



Need help selecting a filter?

See our guide to help you select the most suitable filter for your needs.

Technical Support

How it works

See how the Separ filter works to separate water and particulate from fuel. 

SWK2000 flow diagram transparancy

How to Order

Call or email us to place your order. We accept ALL major credit and debit cards, bank transfer and also PayPal. 

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Expert advice

Unsure which spare parts you require? Or if a Separ filter will meet your requirements? 

Talk to our expert team. Call 01923 276 007



Delivery options

We have a wide range of shipping options available to suit your destination and budget.



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Contact Us

3 Kingley Park, Station Road, Kings Langley, Herts, WD4 8GW

Tel: +44 (0)1923 276007

Fax: +44 (0)1923 267463

Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

Here to Help

Product guides

Fuel Specs


Selecting a Filter