howtobrew wrote:Remember, this spreadsheet is all about arm waving.
That is a very key phrase which so many chose to ignore. What it means is that you can use the spreadheet's color calculations to give you a rough idea as to what sort of beers might have traditionally been brewed with a water of given alkalinity/hardness balance.
howtobrew wrote:You use the Color of the final beer to estimate how much alkalinity is required for the mash pH.
"Required" is a very unfortunate choice of words here.
howtobrew wrote:Stronger beers of the same color would have more aciidity and therefore coul tolerate a higher RA, than a weaker beer.
"Tolerate" is a much better way of putting it but the statement is still iffy because the color tends to come from the malts that produce acidity. So a strong beer with a pound of roast barley in it would have about the same color as a weak beer with a pound of roast barley in it and the roast barley would contribute the same amount of acid to both.
howtobrew wrote:I use the Morey calculation for color btw.
This implies that the SRM/RA fit was derived from calculated color and RA values and not from measured data. This makes it even squishier. I have tried some fits to measured color and find a slope 1/7 th of what is in the Palmer model.
howtobrew wrote:Using the weighted average of Lovibond of the malts is not recommended because of the way that SRM is actually measured. Dark beers have to be heavily diluted to allow light to pass thru them for the spectrophotometric test.
It's true that dark beers are diluted in making the SRM measurement but that has little to do with the validity of the model. Beer's law does (in all my experience) hold for beer and thus you can dilute as much as you want and still get a good color reading. Where the method of adding Lovibond ratings fall down is
1) The colors specified for the individual malts are for Congress Wort. In your brewing you are not making Congress wort. You are making it the way you make it. Decoctions, extra long boils, thick mashes, direct fire vs steam, bicarbonate content ... all change the color appreciably.
2) It is not clear what the "official" relationship between SRM and Lovibond is. Taking what is on Weyermann's website as gospel they are about the same at low color levels (the parameters in the SRM definition were chosen to insure a good match between the two scales for light beers) but differ appreciably as color deepens.
[quote = "acepilot"]OK, run all this shit by me one more time. If I'm brewing a beer that will have an estimated SRM rating of say 15L, but my mash tun will only contain say Pale Ale Malt at about 3L, with the remaining "SRM" coming from all other grains that have been steeped, should I adjust the mash water to be suitable for an SRM of 3L or the 15L? I would think adjust for 3L....
[/quote]
The best thing you can do is forget that you ever heard about a tie-in between SRM and RA. If you are brewing something like an ESB (about 15 SRM IIRC) you should think about what Chiswick water might be like and, if you do anything at all to your water, try to get something that is generally like Chiswick's. But then you don't know what they do to Chiswick water to produce Fullers. They very probably add acid to get mash pH into the right range and they may decarbonate the water before brewing with it. So when you adjust to emulate Chiswick water you are actually trying to emulate conditions that might have pertained at the time ESB was originally developed. To make a decent ESB all you have to do is get some RO water and add a tsp of calcium chloride to 5 gallons of it. A tsp of gypsum is optional and should be used if the resulting beer is more to your liking with it included.