What's the best way to clean Algea off vinyl siding?

Soap and water should take it off, Tammi.

We rent a pressure washer every year!! Works wonders for stuff like that. Check out my post on where and how to rent one with before and after pics. : https://karupp-did.net/power-washer/

Hello. Preventing—Its likely due to your environmental conditions. Tree removal could help by allowing more sun exposure.

Power washing with appropriate solution ( house deck concrete driveway) helps our situation. We have a waterfront exposure two decks and a boat dock-theres high humidity and droplets on our decks and rails each morning and the results are mold and mildew. Its a yearly chore for us.

This product in particular is effective-is labeled fabric, plant and turf friendly.

It is a cleaner with Oxiclean bleach.

Please check customer reviews +Q&A to see if it might meet your needs.

https://www.amazon.com/Scotts-Outdoor-OxiClean-One-Gallon-Concentrate/dp/B00T3ZO06I/ref=cm_cr_arp_d_product_top?ie=UTF8

Dollar Tree...Awesome Orange & a hose

Try Krud Kutter

Just a light bleach and water mix spayed with pump-up sprayer, will do just fine regular house hold laundry bleach is all you need,1/4cup to a gallon of tap water should be fine. Alge is the same as swimming pool Alge and house hold bleach will kill it. Spray all the surface then rinse off after a 3-4 minutes. Reapply if regrows which is not unusual its Alge / Sunlight moisture is what causes it to grow just like in Ponds, Lakes, and Swimming Pools that is why using Bleach in pools keeps out the Green. Good Luck! it will be fine/ Tr.