Pressure washers have the uncanny ability of ruining your decks. When the wood dries up after the cleaning process is over, you will be horrified to find out the amount of damages the pressure wash had caused to your deck. The more damaged parts look as if they have sustained sunburn for a pretty long time.
In such cases you will be left out with only option of renting a power sanding machine. You must sink all the nails properly before you start the power sanding. Initially you will use coarse sandpaper to rub the deck area and then convert to medium or lower coarse sand papers. If the pressure washer has not removed all the wood stains the sandpaper will.
However, to be on the safe side it would be better for you if you use the aluminum oxide sandpaper. The reason is that such sand paper is self sharpening. Other deck cleaners cannot be used on such decks. That is why it is always better to use oxygen bleach or such components for cleaning your deck that does not sustain damages as caused by the pressure washers.
You should also remove all dust from the platform before you use the sealers. But before applying the sealer read its label and find out whether it is epoxy resin sealer and water based. These types of sealers are the best but the first coat should be thin and you will have to apply two coats to get the best results.