I am a first-time pool owner and am maintaining it myself - haven't taken the leap to BBB yet but am considering for next season. A couple times a month, I take water to my pool builder's retail store to compare results to my TFT-100 kit. Pool is ~15,000 gallons quartz plaster and I am using ProTeam 3" tabs, ProTeam Supreme Plus (borate kept at 50 ppm) and ProTeam Shock as needed (plus muriatic acid and baking soda when needed). My tests are usually pretty close to pool store's except alkalinity. For example, I tested my levels on Sunday and within an hour, without swimming, I took a sample to store. My alkalinity measured 110ppm using TFT-100 and theirs, which denotes "w/stabilizer correction" measured 72ppm. Do you know what they mean by stabilizer correction and is there a formula (or even a need) to do this? My pH seems pretty consistently on the high end (has gotten up to 8.0 but I brought it down with muriatic acid).
Any advice appreciated. I will call pool store tomorrow but thought I would check with y'all first.