Bromine tabs will lower the pH if there is no carbon dioxide outgassing. So if your TA is higher or you have more aeration, then you can have pH balance or even the pH rising. So if your pH tends to consistently fall over time, you can raise your TA level (within reason). I wouldn't go much above 120 ppm unless your CH level is low and you don't need it higher to prevent foaming. I'll bet that having a TA in the 80-100 range might be sufficient for better pH stability, but it really depends on the amount of aeration and use of your spa.
For a short term increase in pH, you can add a base such as 20 Mule Team Borax or pH Up (Arm & Hammer Super Washing Soda) where the latter will raise the TA more than the former.
Remember to measure your pH at a consistent point in time, such as just before your soak. The pH and bromine levels vary quite a bit during and after your soak especially after you add an oxidizer to the water. The pH and bromine level will go up after adding an oxidizer and will come back down as your bather waste gets oxidized.
For a short term increase in pH, you can add a base such as 20 Mule Team Borax or pH Up (Arm & Hammer Super Washing Soda) where the latter will raise the TA more than the former.
Remember to measure your pH at a consistent point in time, such as just before your soak. The pH and bromine levels vary quite a bit during and after your soak especially after you add an oxidizer to the water. The pH and bromine level will go up after adding an oxidizer and will come back down as your bather waste gets oxidized.