Stay away from swinging arm hydrometers for those who have them. You alk is low compared to calcium. Where is your magnesium? If its too low it might be causing your alk to precipitate at very low levels, and once again like already mentioned low alk levels could be the cause of higher calcium levels. If mag is below 1350, you might slowly want to bring it up to that point or closer to 1400. Take your time in doing so. What livestock are you keeping?