A few things don't make sense to me about what's going on here. If the source of the rising calcium in the pool water is coming from the pool surfaces, then this should slow down and stop when it reaches equilibrium. With the numbers posted, the pool water should be in perfect balance at a pH of around 7.6 and at 8.0 the pool water should already be over saturated with calcium carbonate. I can understand the initial rise from 140 to 350, but do not understand why it is continuing to rise.

The other piece of information that does not makes sense is that adding 40 ounces of Muriatic Acid to a 12000 gallon pool with a TA of 90 and CYA of 55 should result in a drop in pH from 8.0 to 7.12 -- is that what he is seeing? So the pH rises from 7.2 to 8.0 over 24 hours and creates a daily acid demand of 40 ounces of Muriatic Acid every day? This seems extraordinarily excessive to me and since the TA is already somewhat low (a good thing to avoid carbon dioxide outgassing), it would appear that there is an additional strong source of base in this pool. I suspect that the SWCG system is somehow faulty and possibly not dissolving the generated chlorine gas into the water properly, though it would take generation of 6.5 ppm of such chlorine per day to explain the numbers (and that seems too high).

Are the posted numbers correct? Especially the 12000 gallons and 40 ounces of Muriatic Acid daily?

Richard