I'll let someone else help you with the pump/filter issue.

What kind of a test kit do you have? What kind of pool is it?

Low pH is a critical problem. If it is reading at the bottom number on your scale, it could be much lower. Readings below 7.0 are acidic and can damage your pool! The most concerning thing is that you are getting such a low reading while your chlorine is high because typically when the chlorine is high, you get falsely high pH readings. You can use 20 Mule Team Borax (laundry aisle at Walmart) to raise it. What is the volume of your pool?

Your chlorine will come down on its own. How quickly depends on what your CYA reading is.