Revisiting pebble tech's warranty card, it reads "Do not chlorinate your pool until water is filtered and pH and alkalinity are acceptable. Chlorine is highly reactive and can cause metals or minerals to precipitate (cloud water, scale and/or stain)." As I know chlorine would dissipate quite fast added mid day, I first added 22.4 fl oz of muriatic acid to lower pH, which I assume will also lower TA.

I hope when I retest in late afternoon that TA will be no lower than 80 and pH at most 7.6: I can then add chlorine (using 8.25% bleach) at dusk. Tomorrow I can add cyanuric acid to the 25ppm that my installer recommended.

I will update. Hopefully I do not have to keep adjusting TA then pH for too long. I suspect running my filtration system continuously at full speed (as per installer's directions) aerates the water and increases pH: this should stop once I reach 7 days after fill up this Wednesday and drastically lower the speed of my variable speed pump.

Advice welcome!