A few questions:
Why do you think you need to use it?
Do you have a water report?
Have you made water ion adjustments to your brewing water?
The pH issue is only part of the process. Unless you have some really off the wall brewing water it can probably be adjusted with some additions of common brewing salts like calcium sulphate, calcium carbonate and calcium chloride. That insures you have enough of the required ions, especially calcium, in your mash. Once these are balanced for the beer style the mash pH will fall into place.