There was also the not so veiled insinuation that he was unable to taste/understand the difference - this being why he could not notice it in his dark beers
It wasn't intended to be insinuation at all but rather a simple declaration of the well known fact that the strong flavors of stouts/porters mask many brewing errors such as oxidation which make them a good place for beginning brewers to start.
So indeed it is.
My question is how do we mere mortal brewers with limited facilities and plain old - ya know, brew pots keep O2 from touching our wort!
You can't and neither can the high end megabrewers. The best we can do is minimize it and that is what we strive to do.
I do not see how i can have that open pot evaporating away nicely and somewhat necessarily without all that O2 we depend on not to pass out while brewing from reaching that vulnerable surface?
As the temperature of the wort rises in the kettle the vapor pressure of water is rising as well so the partial pressure of O2 over the wort is decreasing. Once ebullition has begun the partial pressure of oxygen has decreased to 0. You are protected. During cooling the the reverse take place but it is clear that if you can get the wort out of there before it has a chance to cool much you will have more protection. This assumes a plate chiller as clearly jigging an immersion chiller around in there is going to disturb the protective layer. If you must use an immersion chiller then a strategy might be to leave it in place and stir as gently as possible with a spoon. Obviously, run as much of the coldest water that you can.
And then - with our lifeless unsophisticated palates how would we ever be able to tell if the O2 demons had infested it all anyway?
I have no concept as to what your palate may or may not be but people with normal palates, or at least those that have had some training in tasting such as that undertaken in preparation for the BJCP exam should be able to tell the difference.
But That i fear is not the issue at hand- instead, the op was curious if his softened water could affect the flavor of his light beers and cause at least a seeming sense of staleness, and once again i say hell ya! Because I have had it happen.
My answer to the original post implied that the poster should look elsewhere for the source of his stale/oxidized flavors. For those who need simple declarative statements: no, the mash water will not cause these flavors. Because the use of a water softener cannot cause hot side oxidation I did not comment on the particular water described in the OP. While it is implied that the 'original' water came directly out of a water softener it clearly didn't, or not one that is working properly, as it contains 3.75 mEq/L Ca++ and 2.1 mEq/L Na+. Were this water run through a softener it would contain only a small fraction of an mEq/L Ca++ and the sodium would be close to 5.85 mEq/L. The 'revised softened' profile isn't softened at all. It is ostensibly simple decarbonated but there is something funny here. Without doing calculations to see of either of those profiles balance I can see that about 5.7 mEq/L alkalinity has disappeared and that only about 2/3 of a mEq/L has appeared to replace it. Otherwise the revised profile is fine for many beers.
BTW - I am sipping a beer that was put to bed, according to the toe tag on the keg, on 12-2-15 So it has just recently passed its 2nd birthday. I cooked it in a pot. I fermented it in a plastic big mouth bubbler! and i stored it in a corny. It tastes pretty good. And I am not getting cardboard or the heebie jeebies from it. But then it is a Guinness Export clone, so I probably can't taste that it is spoiled as hell!
No, probably not. If it resembles the Phoenix (Quatre Bournes, Mauritius) version (licensed by Guiness) it is pushing 9% ABV and thick as molasses (obvious exaggeration there). And maybe it isn't spoiled at all. As I mentioned in an earlier posts beers are still made in which there is hot side aeration. There is a lot of debate on this subject with some feeling that HSA is as much of a hoax as global warming and others being equally fanatical that a picogram of oxygen in a hectolitre of wort will ruin a beer. In any case, you freely recognize that you can't taste the staling which is sure to be there probably as much because of casual cold side handling as hot, OP probably couldn't either and I'm sure I couldn't.
To be clear on the bottom line. OP need have no fear that his new water treatment is responsible for the staleness of his beer. OP should look elsewhere for the cause - not only on the hot side but on the cold side as well.
There is one way in which water can result in beer staling and that is where finished beer is diluted with water containing oxygen. For example a brewery may produce its 12 °P beer by brewing a 16 °P beer and then diluting it to 12 °P at packaging. The dilution water must be as oxygen free as it can possibly be or early onset staling will occur. And I suppose this extends to water used for makeup of water lost during decoctions and in the kettle. In these latter cases it is usually simple enough to run the temperature in the HLT up to boiling in order to obtain some nearly DO free water.