My Kubota recommends using kerosene to clean the filter. I would prefer to change out a fuel filter versus cleaning, but I have back flushed a filter before on severely contaminated equipment before. I was surprised to see any equipment manufacturer calling for washing since most would just dunk the entire filter in the cleaning solution; thus getting lots of debris inside to the clean side of the filter, and the Kubota instructions did not explain the chances of this happening, nor how to prevent it. I stand the filter upright and fill container enough to cover about all but the last inch or so, let the cleaning fluid soak from outside to inside, then pick up filter and let fluid flow back outward, washing away the large pieces of debris/algae/etc. Repeat as needed, and as long as the filter flows enough to not starve the system, and has no tears/rips all is well. I have also used spray carb cleaner, but not too much as it may soften glue holding end caps on, and most of the cleaner needs to evaporated away before re-filling bowl, as carb cleaner has not much lubricity for the injection system. If one has an algae problem, cleaning the filter versus replacing is just as good until the fuel runs clear, instead of going through several sometimes expensive filters, as long as the used filters don't get cross contaminated.