I bought a house two years ago. There is a really nice deck on the whole back of the house. I don't think it has ever been sealed though, since I moved in I have noticed the color changing to a light gray color and the nails are starting to pop up and sink in. What do I need to get to finish the deck? I don't want to change the color at all just seal it so the water stays out. I bought some deck clear sealant but it turned the test area alot darker. And what do I need to do if anything to prep the deck before the application? Any help would be great.