In regard to my sparge water - I treat it exactly as my mash water. So, in my recent Bitter, I used 75% RO and 25% Tap. Added 2 grams of gypsum and 1 gram of CaCl..... Did the same basic thing to sparge water.
I use B'run water to project mash ph. I have used a pH meter to check and cross referenced with the 3-tab colorphast strips...... got consistent results between the two, so rarely use the pH meter anymore as it is a PITA and I am rebrewing the same recipe's with same profiles. My pH (Projected and measured) is always in the 5.2-5.4 range - unless I purposely make it higher for porters, stouts, etc.
I am not necessarily concerned with "crystal clear wort" transfer I guess....... Although, I don't go out of my way to dump all the trub/break/hop particles into my fermenter either.
Just the way my system is. I have a 15 year old, Morebeer, 3 tier gravity setup. The way the spigots are on the pots, and the way the false bottom is in the mash tun - there ends up being dead space. In addition, I have used bottling buckets in the past and currently use stainless brewbuckets for fermenters so that I can avoid siphoning and just use gravity to drain into kegs at end of fermentation (no secondary). The stainless brewbuckets have a conical bottom and about 3/4 gallon is left behind. So, leaving some behind there is a bit more of an issue because I do want to transfer as clean of beer as I can at this point.
With my hoppy beers, it is more of an issue transfering to fermenter, because I don't want to transfer 6-12 ounces of hop material into my fermenter if I can avoid it.
I realize I am "wasting" 1-2 pounds of grain..... but, I can live with $1.50. I get 85% efficiency, so, overall, I am still doing ok even with the deadspace loss.
LIke I said, it is not a MAJOR astringency issue. But, I know it shows up from time to time. I have had comments from judges on occasion about astringency/oversparging possibility. And, I know I am trying to collect too much wort from too little grain...... so, just wondering if this is a viable way of doing things?