First thing I would do is check your tensioner to make sure it works. Grab the tensioner pulley and move it to see if the rubber twists and returns to normal.
If it does, then the tensioner is OK.
As far as the pointer goes, it is on the top side of the tensioner assembly and when the tensioner is in the relaxed position, you are suppose to move the pointer to the left...at the starting point. Then proceed to tighten the tensioner adjusting bolt until the pointer moves to the maximum mark on the scale.

Make sure your lock down bolt is loose and then tighten it back down after adjusting the tensioner.

If all you did was replace the water pump, then everything should go back like it was.

Good luck,

Dave