Jeffrey, more information is needed.
Does the 450 and 580 numbers represent "calcium" hardness or "total" hardness? And what have been the other water parameter readings?
The water could been aggressive enough (with a low pH and alkalinity) according to the LSI to have caused the increase from 450 to 580.
Of course, evaporation is another possibility depending on the weather, wind, etc. But maybe that isn't the cause since the tap water has only 80 ppm of calcium hardness.
Also, very poor quality pool plaster (due to improper workmanship and materials) can also break down and deteriorate (without the pool water being aggressive), and cause calcium from the plaster surface to dissolve into the water and increasing the calcium level.
Adding an excessive amount of calcium chloride and water to the plaster mix, and adding a lot of water to the surface while troweling can create a very weak and porous plaster surface.
All above issues could be considered as a possibility. Tough call. The plaster surface can be analyzed by a cement lab and help in determining the cause.
Having the plaster analyzed by a cement lab, with petrographers, can be expensive and also involves obtaining a plaster "core" from the pool. RJ Lee Group in Pennsylvania, or Wiss, Janney, Elstner Associates are two of the best labs to send samples to. But I don't see the owner willing to go to all of that trouble and expense.
I wish the NPC would adopt better and more specific guidelines and standards to help improve the quality of plaster jobs, including with quartz and pebble finishes.
I'm not sure how close you are to the DFW area, but if you want to lower the calcium (among other things) without draining, give Jim Calkins of Weber Pools a call at 817.680.4842 He operates a mobile Reverse Osmosis system in that area and could definitely help.
I'm sorry that I can't help you with the source of the rising calcium!
Our fill water is 110 ppm, cal hardness . A customer had pool replaster 1 season ago end of season total cal hardness 600 ppm. could water been so aggressive in that short time it could pull and add caliprofanity filter removed this wordto that level ? It is not the first time I ran into this . little cal hypo was added in one season.
Iam really asking can plaster put caliprofanity filter removed this wordinto water if so Why ?
Pool plaster is made of mostly calcium compounds. Therefore, if the water is aggressive enough, it can certainly dissolve and etch the plaster sufficiently to add calcium to the pool water. Very aggressive water will do it more quickly, while less aggressive water would remove calcium more slowly.
You can easily manage a pool with 600 ppm CH by having a lower TA and pH target. Also, if the pool has a pool cover during the rainy season and a cover pump, they should put the output of the pump into the pool assuming there is an overflow drain. That is, they should use rain dilution to lower the CH level though again they can manage at the level they are at readily.