I have a 10 year old deck that has some wear and had significant mildew/grime buildup. We applied Defy epoxy uv sealer 9 years ago. We have replaced damaged boards, power washed it clean and plan on sanding. 1) is the cleaner and brightener step needed. 2) if yes, would you sand before or after the cleaning step?
Sand first then apply the cleaner and brightener to finish the prep after. It will help the new stain penetrate better.