Neither the salt mix nor water changes will affect the pH level, assuming the alkalinity level remains in the acceptable zone. If the pH measurement is correct, the issue is carbon dioxide. Running a refugium on a reverse-lit schedule might help with the pH during the night. Other than that, adding a large room-level carbon dioxide scrubber or air exchanger would be the most likely approaches that could help, although they are a fair amount of expense and trouble.
Already tried the Co2 Scrubber . Right now have air intake coming in from outside to skimmer .
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