Are you using the Dichlor-then-bleach method? You indicated before that you started with pool water in your spa so got the CYA that way and then used bleach, so essentially you are on that method. So you should have the TA be lower at around 50 ppm and also use 50 ppm Borates (usually from boric acid) as that should help keep the pH from rising as quickly. If your spa water is fairly isolated, then this should be fairly easy to do. If your spa water mixes too much with your pool water, then it will be hard to have the TA be that different in your spa and your pool, though Borates could be used in both if you wanted to do that (though that's more expensive, given the volume of the pool).