If day 1 is 520 and day two is 580 and your not dosing anything or doing a water change then thats a big red flag that there's a testing error .....because that's physically impossible without manually adding the calcium
Testing your calcium daily is also not really all that possible or at least accurately anyways unless your dropping 2 to 3 alkalinity dKH perday which heavily stocked tanks can do but without the alk drop calcium won't be dropping that much in a day without a noticeable drop in alk and the average kits margin or error is to high for daily calcium adjustments (that's where the saying dose on alkalinity number not calcium numbers comes from )