The solution started as a Spent HCL liquid with a PH of zero, soda ash was added and brought the PH level to a 5.6. After continuous mixing for 4 days with air the PH was retested and the result was a 0.9. What would cause such a loss in the PH of the solution? Also when the PH was reading a 5.6 the solution was dark green in color, after the mixing period the solution is a burnt orange color.
