I've been brewing all-grain BIAB for about a year now, and I've been getting this harsh (possibly astringent) off-flavor in my beers post fermentation. I assume it's chlorophenols from the chlorine/chloramine reacting with the yeast, but I've treated the batches with Campden tablets and even phosphoric acid %10 (about 30ml per 3 gallon batch). I also added salts, such as CaCl, Gypsum and Epsom to the mash based on a "balanced" profile in Beersmith. This last batch was an Anchor Steam clone with a basic grain bill of 5.6 lbs 2-row, 8 oz C-40 and 8 oz of C-60. I used Mangrove Jack's m54 and pitched the yeast at 70 degrees and fermented it between 65 and 68 degrees in my temperature controlled mini fridge.
I've tried using distilled water and spring water, and I believe the spring water yielded my best batch. However, I am confused as to why the Campden tablets are not working if the flavor is in fact chlorophenols. Also, if I'm hitting a pH reading between 5.2-5.5, where is this astringency coming from?
I am stumped. Please let me know where I'm going wrong.