Whats a good product to spray on house vinyl siding to remove green mold and keep it off ?

I can't help you with the water hose method, but I have seen people remove such mildew using a solution of soap and bleach in water. The soap holds the bleach to the surface of the siding so that it doesn't run off before killing the mildew. I would think this method would be better than trying to blast it off for the same reason.

Don't know how well it works on Vinyl but it Copper sulfate worked well on brick work that like yours was on the north side and shaded by trees. This is more of a preventative than a cleaner. For cleaning I would go with TSP and bleach applied with elbow grease and a scrub brush.

Jimmie

A garden sprayer pumped up goes far, some come with different nozzles you can switch out for distance spraying

Household ammonia use a mixture of ammonia and water.Ammonia and bleach are equally = effective weapons in the battle against mold and mildew. However, each = has its own distinct applications, and under no conditions should the = two ever be combined.Ammonia can stop mildew just as well as bleach = without causing discoloration

Dissovle 3/4 cup TSP in some hot water. Add water to make 1 gallon and add 1 cup household bleach. Clean a 10x10 foot section at a time allow the bleach to work for a minute or 2. You may need a brush.

If you have trees causing heavy shade, consider thinning some branches out and give the wall more sun light.

A garden/lawn sprayer attaches to the hose (used for soluble fertilizer), you adjust to fan spray and soak the wall (diluted bleach mix? ). Work from the top to bottom approach, rinse often to avoid streaks/streaking of the vinyl .

Give Bob a cigar-- we used to have a home repair program on the radio here, and the guy recommended Jomax for cleaning siding before painting. I doubt the OP is going to paint his vinyl, but I would think Jomax should do the trick in this case as well Larry