OK for starters, you'd better add 1 gallon of plain 6% bleach per 10,000 gallons of pool water this evening, and again in the AM. Keep dosing 1 gallon per 10K in the PM, till you work something out with your installer. But, don't let it 'go green'!

Regarding the pH, it's normal for pH to rise as plaster cures. But, different contractors have different ideas about how you should handle that . . . and your plaster warranty is partially dependent on doing it HIS way. So, track your guy down, and find out what he wants done.