The rise in pH mostly comes from carbon dioxide outgassing and that can be minimized by lowering the TA level. If you lower it a lot and want more pH buffering, you can use 50 ppm Borates. If your fill water is high in TA, then evaporation and refill will increase the TA over time (same with CH). Basically, evaporation and refill adds whatever is in the fill water to your pool. pH can also rise from fresh plaster. It also rises from the excess lye in chlorinating liquid and bleach, though the amount varies depending on the quality of such product (some have lower excess lye -- Clorox Regular has some of the lowest; off-brand bleaches tend to be higher).
Remember that pools are intentionally over-carbonated to provide pH buffering (ironically) and to saturate the water with calcium carbonate to protect plaster surfaces. However, TA is a SOURCE of rising pH due to carbon dioxide outgassing.
This post shows the equilibrium pH at various adjusted TA (carbonate alkalinity) levels so shows the pH at which carbon dioxide outgassing will stop. In practice, it slows down significantly before then so I also show the pH at which there is twice as much carbon dioxide in the water as compared to equilibrium with air. As you can see, even our lowering the TA to 70 or 80 ppm still has the pH rise and even at 50 ppm it still would rise, but the rate is much slower. Usually, though, 50 ppm is only a TA level needed in spas where there is a huge amount of aeration when jets are used.
