algae and too low ph

[Danak]

OK I have bought the unicel filters and hth6 way test kit and BBB....here are the test results.....
Chlorine 5
pH 6.8
Alkalinity 80ppm
Hardness 120 ppm
Cya when I read the view tube it is at 30 ppm but I can still see the black dot on the bottom.
Still have very cloud green water. Draining and refilling is not an option.