Guidance for deck prep

Hi Scott,

Thanks for all the informative articles on your site. We have a six-year old treated pine deck which was professionally stained with semi-transparent water-based S&W SuperDeck five years ago, and then I washed and re-stained the horizontal surfaces (with the same stain) two or three years ago. As you can see from the pictures, it is peeling terribly. It is a high-traffic deck, mostly shady, some light mildew, in central Ohio. It seems clear that we need to go with a solid stain, probably one of your top three - I'd like to keep the redwood color if possible, or something close. Do you think that the old stain needs to be completely stripped and/or sanded, or just the peeling areas? (The vertical surfaces don't look bad.) Then I assume brightener, light washing and then stain? Thanks for any advice you can provide.