Review on 🧪 ColorpHast 9590 pH Test Strips 0-14 by James Brault

I bought these strips to test drinking water from a residential well and when the pH of the water was around 7.5 to 9.5 these strips showed around 6.5 up to 7.5. They could show two points lower when the base was in those areas. Once the pH got past the 9 or 9.5 mark they seemed accurate again, but I haven't tested this with a known accurate strip or meter to know for sure. They also seemed accurate for acids. It took me about half a day to figure out what was going on as we tried to get the water to pH above 7 but maybe not above 9.5 to help the Katalox Light filter tank, iron and manganese to remove. The most inaccurate area of the strip was right in the area I tested; I couldn't figure out if our gear (calcite/corosex tank) was failing or what was going on - I ended up calibrating the meter I had on hand and testing the water samples with this and a few other strips I had. manufactured by Aquachek (Khach). I learned that these streaks were neutral (or even slightly acidic) when they should have shown weak base. My strips have the date '08/2013' printed on the bottom of the box, maybe they had expired when I received them (if not actually the date of manufacture) and is this related? I do not know. In any event, I have since purchased several Machery Nagel strips (albeit in the 7-14 range) and they work perfectly and match my glucometer and other Aquachek (Hach) strips that I also have.