Good evening. Not new to the hobby but have a newer tank. Past cycling and been placing corals in now for a month. System is 80 gallons total. I have been doing water changes on average every 5 days roughly 12%. Test my parameters today my cal. Is 380 dkh is 7 and mag. 1200ish. How do I raise these back up and what could have dropped them so fast? I did get saltwater from a different fish store wondering if they had a weak mix? Was using small doses of Kalk dripped into my ato. I also have no coraline algae. Could it be taking off and absorbing really quickly. No big colonies of corals btw. Thanks in advance.