Before I had my pool/spa combo built I had a stand alone hot tub for many years using bromine. The biggest problem I had was that the constant airation would tend to cause a pH rise while lowering the alkalinity. What worked for me (after MUCH trial and error) was to adjust the alkalinity first and then lower the pH to the upper end of acceptable (I shot for about 7.6) After reading the FAQ on how to lower total alkalinity here on the forum (before the GREAT CRASH of 2006!) I realized that I was probably doing the right thing. Once again, with the small water volume in a spa it becomes crucial to know the exact amout of water as posible because your dosing might be in teaspoons insead of ounces!