I do trust my thermometer. I should calibrate it although i dont think it's off by much. It's a relatively new issue for me, I've never tested my ph before but when i was using cooler water to sparge astringency did not seem to be an issue. I did make a stout and a brown ale in November that had some minor astringency initially but got better after a few weeks. It was a milk stout and a spiced brown ale with molasses, guessing the additional sugars mellowed the astringency. My reason for posting is that i've been told a higher sparge temp should not be an issue and Ive also been told the opposite. I know several brewers around me that don't make changes to the city water ph and don't have an issue.