The Kilcher Homestead is a 600 acre Pioneer Homestead that has been protected for perpetuity via a ConservatIon Easement. The Kilcher Family has also preserved the Historic Cabin and site as a LIving Museum.
Yes, negative pH is possible, but not in water as a solvent. The range of pH in water is 0 to 14 (to be more precise, it is -1.7 to 15.7, but for simplicity's sake, we start with the usual values.) Thus, what pH indicates is the ability of the acid to form H3O+, which can then donate a proton.
If your pool pH is less than 7.0, then hydrogen peroxide is much less effective. In our opinion, if your pool pH is this far off, then you need to address the low pH first. Keep in mind that if you destroy the chlorine in your pool with a chemical, the cyanuric acid level will remain the same.