You'll just have to keep filtering to try and clear the water. We don't typically advise using soda ash. Instead, we use 20 Mule Team Borax (laundry aisle at Walmart) to raise pH.

I think you have some testing errors with your chlorine as I really doubt that you have a CC reading of 5.2 or 2.6. Can you please tell me what steps you are doing to test your FC and CC?