[asylumdown]

ah I see, yah that's normal algae then.

Well, calcium chloride (if that's what you're using) inherently doesn't cause the issues you're talking about, otherwise it would be the most common problem experienced by hobbyists. That leaves either

a) a contaminant in your supply
b) The calcium causing other issues with your water chemistry - dying tips is often associated with alkalinity problems, any chance you've had periods where your alk has been driven too low by the addition of calcium? Each test we do is only a snapshot in time, perhaps your dosing of calcium has caused swings in alk? They're pretty good at surviving within a pretty wide range if it's stable, but they're not awesome at dealing with rapid changes. Overdosing on calcium can cause sudden drops in alk which can burn the tips of corals, and takes a very long time to recover from
c) this has nothing to do with the calcium and it's a coincidence that things seemed to briefly improve when your calcium reservoir ran out.

case a is easiest to test, toss what's left in your dosing reservoir and make a new solution with a different brand and see if that helps. Case b can only be tested by checking your water chemistry every day to make sure your alk is stable day over day for a long period of time, though if this is the aftermath of a period of instability that has passed, you might not get a conclusive answer. Case C is the hardest to test.

If you really want to find out if the calcium is the problem, I would personally start by changing brands and testing my levels every day (maybe twice a day) for a couple of weeks. Simply ceasing to dose calcium won't tell you what the issue was - even if things improve, that won't tell you anything useful. If it improves you'll still be left with it either a) being a coincidence of timing) or b) it was something to do with dosing calcium, but you still don't know what. You'll need to dose calcium again in the future eventually if you've got stony corals, so it would be better to know how to prevent this from happening again when you do.