OK from this previous thread (http://www.homebrewersassociation.org/forum/index.php?topic=14292.0
) I am realizing that my processes are a little abnormal compared to the average homebrewer. To recap, the main issue is my large kettle which has a huge (30-40%) boil off rate, which caused me (up until my most recent brew yesterday, Maibock) to oversparge... that is, collect 16-17gals to boil down to 11gal. This caused astringency in many beers even though I got great efficiency. Then the astringency from oversparging got further concentrated by the boil.
So based on suggestions from this forum, I sparged only until I collected 12gal (which would put me in the ballpark of other 10gal brewers, I guess), then I added 5 gallons water to the kettle before starting the boil (for various reasons it is basically impossible to reduce my boil off rate, in case you're wondering). (I also acidified my sparge water with lactic acid for the first time, getting in from ~7.5 down to ~5.7, which will help astringency also)
Now I use Kaiser and Martin's water spreadsheets heavily. What I did yesterday was add minerals to the "dilution" water (which I added to the kettle pre-boil) in the same proportions that I did to the mash and sparge water. Thinking about it more, I think this may be wrong? If I enter data into those spreadsheets as if I'm collecting 12gal pre-boil, that obviously makes my mash pH and everything work out, as well as setting the flavor profile. So if I add more
minerals preboil, I am now thinking, that screws everything up and sort of "concentrates" my minerals. Perhaps what I should be doing is adding distilled water as my dilution, so the minerals don't get played with... because the only reason I'm adding water to the boil is so I have enough wort to ferment after the boil.... so it just be be distilled that evaporates off... correct assumption? Or am I off here? (previously, I entered data in the water spreadsheets as if I was collecting 16-17gal, and they nicely gave me lots of stuff to add to my sparge water, which again got concentrated in the boil... if Martin or Kai could clarify how their sheets work it would help here... I guess they assume most people have a "normal" boil off rate)
So that got me thinking further: I bet I'm messing with my hop utilization by having such a big preboil volume.... so maybe instead of adding 4 or 5 gallons right at the start of the boil, I should add it a half gallon at a time during the boil, so I never have more than maybe 12-13 gal in the kettle... this would then let me mimic the average homebrewer who boils from 12 gal down to 10.5, or so...