Now, for the result that everyone has been waiting for...(chirp, chirp).
Anyway, I didn't have time to taste my Batch #4 last night, so I had a little sip today at lunch. I was so nervous since this was such a critical moment. After going through all of the information in my previous post I realized what a big deal this problem is. And if Batch #4 didn't work out then I was at a dead end in terms of fixing the problem.
The good news is that I tasted Batch #4 and it DID NOT have the bitter taste that was present in Batches #1-3. It tasted like a real Hefe!
Now, before everyone gets excited, I think there are two reasons to bring some skepticism to the table. First, I want to see if the taste develops with age. I don't think it will, but this batch is only a week and a half out of fermentation, and I don't remember at what point I tasted the bitterness in the other batches. Second, Batch #4 is a wheat beer with a very unique hefe yeast. So in my mind it is a bit different and may not be fair to compare one-to-one.
However, I have now have a great deal of hope. My plan is to take the water adjustment technique from batch #4 and apply it to a new batch using a recipe from one of the earlier overly bitter beers. So, in other words, I should have results in about two months, haha.
Assuming, however, the problem is identified and solved, the recommendation based on my experience is to use chapter 15.3 of How to Brew to get your sulphate:chloride ratio in line (of course, keeping everything else in check as well). The calculator on brewersfriend.com is a real help and I would highly recommend it to anyway, since going through those calculations by hand is tedious and very error-prone. And as was mentioned already you really don't want to mess it up.
Brewing Water Chemistry Calculator | Brewer's Friend
Lastly, as further evidence, it would be nice to see some postings on mineral content levels from people who are experiencing this problem. At a minimum we need
Ca+2
Mg+2
SO4-2
Na+
Cl-
HCO3-