Yeast, Mould and Bacteria
Collectively known as microbes the formation of the above is whay we commonly know as "the Bug".
Microbes are single cell organisms, millions of which can fit into the eye of a needle. In fact there are more on your hand than there are people on the planet! They are naturally present in the food we eat, the air we breath and the ground we walk on.
They naturally occur in fuel stock and can also be introduced from the air.
These microbes feed on water and other nutrients present in the fuel stock.
It is "blooming" or massive uncontriolled growth of these organisms can can cause the formation of sluges, slime and the associated blockages in our canal boat fuel systems.
Water presence in diesel is a major contributor to Diesel Bug.
Biodiesel is bad news due to its natural susceptibility to water contamination, but normal petro-diesel is also vulnerable.
Water is heavier than diesel so condensation that forms in the tank will settle to the bottom.
It is at this interface of water and fuel that microbial activity can occur. Waste is formed as a result of this microbial reproduction and as they die they form into black, sludgy clumps.
Algae and fungus can grow on these dead clumps of microbial waste and the result soon multiplies into what is known as a biomass.
The biomass can either be suspended in the fuel or settle to the bottom of the tank. Either way as soon as it gets into the fuel delivery system it will cause major issues with filter, pump and injector blockages.
As soon as the level of dead microbes reaches the fuel pick-up pipe in the tank and they start to flow into the fuel delivery system, you will have problems.
Diesel, whether FAME or petro-diesel, will deteriorate over time. In fact a major oil producer recommends a shelf life for standard petro-diesel as only 12 months.
Oxidation is a natural chemical reaction involving a substances reaction with oxygen.
Resultant sediments will form in the tank and not be able to pass through filters , eventually causing blockages and problems.
Rust and other Debris
Rust will form on the inside walls of a steel fuel tank. As most tanks on canal boats form part of the structure of the stern, they are constructed of mild steel.
This rust, or iron oxide, will settle in the bottom of the tank, become dispersed during filling and motion and will eventually cause blockages to filters and delicate fuel injectors.