cleaning off the Gray

I use bleach!

Gray, like unfinished wood gray? Brightener.

Brightener
I tend to use Cabot's

Most likely the gray will come of by just pressure if it hasn't been sealed in. Although you should use bleach and maybe wood brightner.

Cabot's Brightner or Deckscapes Revive, whichever store is closer

Restore-A-Deck. LOL

You should use a percarb based cleaner followed by a ph balancing stage (brightener). LOW PRESSURE ..

I would use bleach

I use Sodium Hypochlorite (liquid pool bleach) 1/2 gallon tor 1 1/2 gallon of water in a pump up garden sprayer. For heavier stain increase the pool bleach formula. (Warning: this will strip off the existing wood stain if applied directly)

I've also used oxalic acid crystals 1 cup crystals to 2 gallons of water. Same garden sprayer application.

Gently powerwash off.

Hope this helps.

Rick

You can also try Jomax mixed with bleach and water in a garden sprayer.
1 Qt. Jomax
2 Gal. bleach
Rest water.

*Note: If you spray overhead. You will want glasses and something on your head. It will burn you eyes and bleach your hair. Trust me I know.