hope you have better luck than I did mine lasted a week , was beautiful before it just died off was fine never showed any signs of stress shut lights off to put fish to bed next morn the coral was dead no warning at all now I just stay with the branching type they seem to like me better , mine was a hammer I am seeing coral on the decline lately especially from the east coast , nothing looks as good as they should , now I'm holding off for a while to give it time for things to improve
As for calcium I don't think there any different than the branching type so they should be ok with whatever calcium is in the tank from water changes
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