Create a mix of bleach and water 1 tsp.
How to remove algae from aluminum siding.
If mold or mildew is the culprit spraying with a bleach solution will remove it.
Spray this mixture on remaining spots.
Water stains remove with a mild detergent and water.
Wash the whole house with a mix of common laundry detergent and water through a presser washer once a year.
For those tough spots use a gentle.
To clean aluminum siding having mildew use a solution of one part bleach and four parts water.
Stains on wood cleanse with mild detergent mixed with water.
Choose a cleaning solution that is appropriate for the type of growth you have on your siding.
To 1 quart and use it in the same power washer as step 1.