This is my problem - ngQ(uestion):
I was taut in skool that pH and alkalinity was the same scale. The number is determined from the definition regarding the hydronium ion concentration, and math or something like that. The pH of neutral water is about 7. That it, it is neither acidic nor base in its chemical character. If the number is low, like 3, it is "acidic" and if its high, like 9, it is alkaline (base). But if it is acidic (low number on the pH scale), by definiton it CANNOT be alkaline at the same time, or vice versa: it cannot be alkaline and be acidic too.
So why are there two scales on these (pool) water test strips, which read from low to high for both pH and Alkaline? There is a pH and a Alkaline scale!? So according to the pool companies you can have a low pH and a low alkaline pool at the same time, or high & high, or low & high, or high & low.
Because I go to the chemical cupboard for the right chemical to fix the problem (assuming all other parameters are being considerately moderated too) and I find chemicals labelled "pH Up", "pH Down", "Alkalinity Up", and "Alkalinity Down"! And I don't want to do anything, (a) because the strips may be wrong (via expiration) or (b) the pool chemical companies may be full of crud.