I thought the Frog was a floater....not in-line. Sorry I misunderstood your first post.

Getting that tri-chlor out of your pool will still make a difference in your pH...sometimes a fairly dramatic difference. That coupled with the Borax should have you where you want to be soon. (Although, I would be comfortable with a pH @ 7.0-7.2 as long as it was tested pretty often and it sure sounds like you do.)