6ml of AFR would hardly be noticeable, alk and cal decrease at about the same rate generally, if you have a lot of growing corals then you may need to add much more than 6ml a day.
You will only notice a calcium increase or decrease over about a week or more, not day by day as most cal test kits are not that precise and also user error.
I would, if you haven’t already, stop dosing for a few days to give the AFR you have already added time to convert to alk then see how much alk your tank uses in 24 hours, then dose the correct amount of AFR.
I would then use alk to determine the correct dose from now on and only test calcium every 2 weeks or monthly, as long as calcium is within a range it’s good, you do not need to get it within say 10mg/l as you would with alk.
Sounds to me you are testing too much.
And yes calcium and mag would show up when added.