Sealing and Staining
After cleaning, you may want to think about deck sealing to protect it and provide a longer lasting cosmetically appealing look.
Clear Sealer: Sealing is basically a clear oil-based product, which soaks into the wood and prevents water from penetrating deep into the boards. Water will bead on the surface for some time, but then the surface beading will wear off. The wood is still protected from rot for a few years. The manufacturer states 5-8 years, but usually the sealer will appear to have worn off after 18 months or so.
A clear sealer will only very slightly change the color of the wood. It may be hard to tell the deck has been sealed unless you sprinkle water on the deck and look for beading.