...and getting a test kit for Ca
to see where you're at in the first place.
I've recently tried to get my Ca
levels up. In a nutshell, no matter how many or large of PWCs I would've done, it would've been impossible to raise my levels to 400 as my freshly made water was coming in around 360. Before I put a single thing in my tank, I got a test kit to determine what the Ca
levels were in my tank, as well as in my freshly made salt water. Only then did I do anything to alter the levels.
Now, I've got my tank between 410 and 420 with alkalinity at 9 dkH
(which is something else you're going to have to test for if you start altering your Ca
levels) and know exactly how much Ca
I need to add to my PWC
water to keep it at that level, as well as how much 2-part Ca
additive to add each day to keep my coraline algae growing strong. But the key to all of it is knowing what your Ca
levels are to start with.
This is the article that made it all "click" for me...
... and here's the link to the "long story" of my battle with Ca
levels, just FYI...