HI,
I have found a product that has trace elements Ca++ and carbonate, it is balanced and is slow to release the ALK buffer when used as directed , I don't worry much about PH or CA++ they have been right on the mark PH is pushing 8.4, and the fish seem happy.
Its called argonite-milk its made from super refined argonite rock that hs been mixed with water, the only down, is if you add it to fast it will precip out into a solid so I let only about 20 drops drop slowly in the water at the water out-put for the sump and it turns the water milky for about 1 hour then clears. Its a no-brainer for newbies and fixes that problem that many skimmers cause of lowering trace, I still add Iodine twice a week.
Here's the blurb ((
CaribSea aragaMILK
The new, easy way to add balanced calcium, carbonate buffer, and essential trace elements like strontium, magnesium, barium to your marine or hard water aquarium. aragaMilk uses the power of natural aragonite for flash mineralization, plus the boost of magnesium to aid in coraline algae growth. No two parts to mix, no risk of overdose. aragaMILK is safe, easy, and effective.))
coraline formation and ca deposits are a indication of good water in my book and cleaning out excess is just part of the fun of keeping saltwater..
here's a pretty basic explanation of that water chemistry.
Reefkeeper's FAQ - Part 1