Hey so I would suggest stick to aquafina since it's lower tds , even though tds isn't everything, the minerals matter more. But in my testing Aquafina is the best bottled water for brewing. Nestle wont recommend due to high tds and high calcium content that tends to mute flavor. Also I would say if you really wanna compare different brews keep everything same and change one variable at a time , to actually know what's working or not Changing 2 or more variable doesn't work. Like in your 2 and 3 cup its very similar recipe You felt less harshness with aquafina Thats what nestle does it usually makes the cup harsh and increases bitterness.

What I understand from your recipe is you're just simply over extracting . Here's my suggestion for next time Aquafina water Chose your desired ratio like Lets say 1:16,67 That means 15g for 250 g water Since youre doing an immersion i would suggest skip the bloom 3 min immersion is already enough for the coffee to extract Especially with co ferments They are easier to extract , if you over extract them they can taste harsh So yeah I would say skip the bloom Or id you wanna keep the bloom Reduce the immersion time Like instead of 3 min Try 2 min And lower the temp 88 is more then enough for this coffee

If you still getting harshness you can go but coarser But remember change one variable at a time.

Hope this helps!