Losing 4 ppm of chlorine during the day is not an indication of a problem . . . especially if you had some swimmers. 1.5 ppm CC might, or might not, be a problem.

Please use this form I created for you, to record your complete pool info (including water condition, filter pressures and calcium levels): PF Pool History - TTorreyson

You can see the results, here: PF Pool History => TTorreyson