Algae is actually a misnomer for what is actually happening. It's apparently a bacterial thing that grows on any water that might be in the fuel. It's more of a problem on a large boat because they tend to carry hundreds of gallons of fuel and with large fuel capacity comes large potential for water contamination.
http://www.boatcoachbob.com/articles-boat-maintenance/engines-inboard/prevent-remove-diesel-algae/It shouldn't be an issue on a motorhome that is properly maintained and gets a few tanks of fuel run through it regularly. A fuel/water separator filter ahead of the main fuel filter is pretty standard these days on automotive diesels and should eliminate any water that might find its way into your fuel tank. No water, bacteria can't grow.
Kevin
