***Disregard most of what I wrote here, as I did not notice it was a conversion***
Well, the first thing I see is that you are not following the shock process. The FC should NEVER be allowed to get below the shock level and you repeatedly reported a FC of 0 ... so you need to be testing and adding more often if possible. Or shooting higher so it does not drop below shock level.
What is your CYA level? I do not see that listed anywhere, so there is no way for me to know what your shock level should be and therefore what FC level is safe to swim at ... you should not swim when the FC > shock level ... which is required while you are shocking.
You also seem to be showing a significant FC drop overnight, so something is consuming your FC and it is not the sun.
So, report your CYA level and then keep the FC above the correct FC level until you complete the
Shocking Your Pool process
EDIT: And why do you keep asking about changing the sand ... there is not reason to do that.
EDIT2: Just realized you are converting ... so there is a reason to change the sand eventually
EDIT3: Ignore the link above and my comments about CYA as that is not applicable. Review the
Conversion article in Pool School. Sounds like you are still in Steps 4-6. You are still loosing FC overnight so it is not time for Step 7 and sand replacement