A digital test for total hardness is only good so long as the machiine remains calibrated . Are you worried it is to high, or low. if is to high the only way is dilution but the catch is it must be done with water that is low in total hardness.
If it is to low the best way is to use a calcium based chlorine produt such as calcium hypochlorite.
As as been previously stated unless it is causing major problems or you are a comercial pool best leave well alone as you will be chasing your tail for ever.
A good test to get is aquatest 7 this does test for calcium hardness they are made by Hach who are also well known for medical test strips, a first class product but not cheap about $ 30 Au.