A level of 400ppm of CH is kind of at the high end, but still manageable. For a concrete/tile/plaster or other hard-sided pool, a CH from 200-400 is recommended, along with a Total Alkalinity of 80-120ppm. The calcium in the water protects the calcium on the walls from being leeched out. For a vinyl pool, CH is useless and can only cause clouding of the water and scaling. But that's not likely to happen if you keep your T/A below 180.
What I would do is lower TA to around 80-100, and, unless your pH starts trending down, keep it there. Try to keep your pH to the lower end of the 7.2-7.8 range as well and you should be fine. You may not lower your CH, but it should be manageable without clouding or scaling.
As for the other stuff--I wouldn't use it unless our owner, PoolDoc (Ben), has a specific recommendation for what to do with it. Ben may also have a recommendation for how to lower CH short of trucking in water, or capturing rain water.
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