Well, the first thing I'd recommend is that you check to make sure the salt water is not damaging your pool. MANY above-ground pool owners are 'losing' their pools in just a year or two, due to the increased corrosion caused by the salt.

Things have gotten to the point that my recommendation would be -- unless the structure of your pool is ENTIRELY non-metal -- that you consider turning off the SWCG, then draining and refilling!

Check and see, but I'll bet you have NO useful warranty against salt-caused corrosion . . . even though the company that sold the pool may ALSO have sold you the SWCG!

Ok. Back to your ORIGINAL question.

There is no "dump it in and the problem is gone" method of removing calcium. There are products that are sold with descriptions that make it SOUND like that's what they do, but that's a deception. What they ACTUALLY do is temporarily interfere with the formation of calcium scale, usually by means of a class of chemicals called "phosphonates". The problem is, due to chlorine and sunlight, the phosphonates eventually break down and turn into phosphates. This then 'releases' the calcium to cause problems again (it was NEVER removed!) AND adds a potent algae fertilizer to your pool!

It is possible to actually remove calcium from a pool, but it's a P.I.T.A (Pain i. the a.) to do so, and requires both accurate testing AND paying careful attention to the process AND doing the necessary clean-up afterwards.

There are several methods I've posted here over the years that work for me and for a few dedicated and skilled pool owners, but don't seem to work for most people. If you want I can explain, but there's no point unless:
1. You KNOW the problem is calcium and not some other mineral.
2. You have a K2006 test kit and have used it to MEASURE your calcium, alkalinity and pH levels.
3. You have a well-functioning filter (sand is best) that passes the DE test.
4. You have an effective pool vacuum, including head, pole, & hose . . . and know how to use it.
5. You are willing to spend an hour per day for probably a week, to actually carry out the process.
Even then, if the calcium is from your fill water (you'll need to test the calcium in THAT water, too) the problem will recur if you have to add much replacement water due to leaks, back-washing, or splash-out. It IS possible to pre-treat the water to remove the calcium, but you'll need something like a 12' Intex in ADDITION to your main pool, so you can pre-treat.