Originally Posted by CosmicJam
I never even thought about water chemistry. What can I add to reduce harsh bitterness in something like an APA?
I use pretty much 100% rain water (only barrier filtered). All I have tested it for is pH and it is surprisingly neutral. Sometimes I use a small proportion of unfiltered tap water which I believe is quite 'hard'.
Check out the Brewing Science subforum.
Generally, sulfates enhance bitterness...so if you wanted to back that off, you'd cut your water with RO or distilled. But you really need a baseline...the Wards Lab $16 homebrew test is pretty key to finding your mineral baseline.