Scott wrote on 23 Sep 2007 in group alt.home.repair:
I actually left of the smiley on my first reply. Of course there are other options to get a non-gray deck. An on-line search will find you any number of clean-up systems that include a cleaner, brightener, and sealer. You spray on the cleaner, let it work, and pressure-wash it off. Then you put on the brightener, which is probably oxalic acid, let it work, and pressure-wash it off. Finally, you put on the sealer. The sealer can be either transparent or colored. You'll still have some hint of gray, though.
If you want the deck to STAY non-gray, you'll have to repeat the process every two years at least. UV light is most of what causes the graying.
The only way to get rid of the gray completely is to remove the top surface of the wood. If you want to use a sander, rent a big one. Cylindrical models designed for hardwood floors would work well, but you have to make sure all the nails and screws are well below the surface first.