I have three different test kits that measure pH (among other things) and I get readings that vary from 7.2 up to 8.2 depending on which kit I use. The readings are consistant within a kit, but I don't know if I should start adding HCl or celebrate for having prestine pH levels (all other levels look good except for too much CYA, or should I not believe it....)
Two kits use a stick test, one uses the drops in solution. I am thinking of buying the kit that TFP recommends...is there a standard out there that is true and tested and/or is there somebody who has verified any of kits? Is across the board readings typical for different kits? And yes, the kits are in a cool, dark place, not expired.