Ok... long story short. New to spa...did Ahhsome a couple of times... rinsed 4 times to get bubbles out. Finally there!!!! Ok now on fresh fill TA at 10ish and ph 7.5. Went to pool calculator and added baking soda at 3oz. TA went to 50. But ph off the chart so added dry acid numerous times. Got ph down to 6.8 and TA didn't register to went back to 3oz of baking soda and yep perfect TA but PH off the chart. So why would ph go from6.8 to off the chart at 3oz of baking soda. 365 gallon. Added no chlorine yet and CH at 200