Finally got a new pool installed after 3 years. (it's complicated; I'll have a complete update in construction later.) I knew that my well water was hard, the aquifer lies under a limestone cap. But fresh water from the well read a TA of 210 with a ph of 6.8. I would have expected a much higher ph reading. I do use the TF 100. Dissolved iron was horrible, I probably could have used a giant magnet to clear it! It didn't drop out with sunlight; raising the ph and adding chlorine did start the process. I supplemented the sand with fiber and used a metal flocculent to get it to drop. Most of it is gone after many scrubbings, vacuumings and backwashes. Why would there be such a divergence with the TA and ph? Doing the CH test, is the change point when the pink turns clear? (260) Or is there a point when it actually turns blue? Being slightly color blind makes titration readings a challenge. I quit at 32 drops.