Stain Stripper darkened wood considerably

Hi all, 

I have a 2 year old house with wood on the front. After this past Canadian winter the wood started graying and the sealer started failing.

I used a Behr cleaner with a nylon brush to clean before water sealing but instead the finish started stripping.

At this point I decided to use a stripper to remove the rest of the sealer and just reseal. 

I used Olympic stripper and tested in the bottom right corner.  It's very watery so it doesn't stay on the vertical surface very well.   After following the directions, I rinsed off and the wood was just a dark dark brown.  Nylon brush scrubbed and it eventually took the wood fibers out of the wood, and after drying a few days is still a gray color.

Any advice is appreciated after my little Sunday morning task turned into a big project.

I have no idea why the stripper is turning my word dark dark brown.  

Also is there anything I can do to ensure the stone floor at my entryway doesn't get discolored?