new swim spa PH wont stay level

[glenda]

My Ph Level is driving me crazy, I have a swim spa 1000 gallon spa, when I get the PH correct the next day it is off the charts again,
I heard we must shower off before getting in pool is this true and if I dont will it effect the PH levels this way, In one week I have use one whole bottle of Ph decreaser. my calcium is slightly low I use the mineral tubes in filters, and treat the pool before and after each use with sanitizer. can you help

[chem geek]

Lower your Total Alkalinity (TA) level significantly down to around 80 ppm or 70 ppm (assuming your Cyanuric Acid level isn't too high) and that should help reduce the tendency of the pH to rise. See this post for the procedure on how to lower the TA.

By the way, what kind of disinfectant are you using? Bromine, chlorine or biguanide/Baquacil? If chlorine, what kind of chlorine -- Dichlor powder or bleach? Are you using a non-chlorine shock (MPS)?

Richard