[BigJay]

when you were using liquid calcium what did you use to raise your alk?

There is really no reason to use anything stronger , but a two part additive is generally easier for people since it tends to balanced in its measurements(ie raising alk in equal parts need per PPM of calcium).
I personally use bio calcium which is a one part that does not deplete alkalinity. But I also have a bottle of calcium chloride (Kent liquid calcium) for when my alkalinity was sky high and I used it to raise calcium while subsquently lowering alkalinity.
I have 20-30 stonies (SPS and LPS) in a 90g and with regular water changes I really need very little in the way of calcium additives. Most tanks realistically if in balance don't need any except water changes.
I'd be curious to see your calcium test results to see why you were needing calcium additives before with only live rock. With standard water changes even a huge amoung of coraline growth would be tough to deplete the amount of calcium in a good reef salt.
As to why there is so many. Its a necessary component. Unlike a lot of other additives that are voodoo or wives tales calcium is not. Luckily for everyone most salt companies supply enough calcium though to meet the needs of the average reef tank. But since people tend to not understand the balance between alk, mg and calcium they tend to precipitate calcium out of solution by shooting for an unreachable number in PH subsquently raising alk and the calcium precipitates out of solution.