My alk keeps dropping with afr

[Miami Reef]

but of course I also do weekly 20% water changes so I figure it can't possibly be too out of spec

That’s the most ideal scenario possible.

If your salinity is around 35 ppt, there is never a reason to test calcium, ever. This is possible because of AFR + your water change schedule.

You can even reduce the water change volume by 50% and still never need to test calcium.

 

[Randy Holmes-Farley Verified Community Expert]

Well the truth is that I dose AFR and don't bother to even check Ca, but of course I also do weekly 20% water changes so I figure it can't possibly be too out of spec

That’s a fine plan, IMO.