fly sparge water pH, not important

[jmo88]

I just listened to the Brew Strong podcast regarding sparging. Palmer was asked if the pH of your sparge water should be lowered to the mid 5 range to avoid tannin extraction near the end of the sparge. He claimed that the pH doesn't matter so much, even if your sparge water pH is 8. What matters is the total alkalinity of your water. Now of course you don't want to sparge with too hot of water and sparge past 1.008. But to my surprise the pH isn't that important because of the residual buffering power still in the tun.

My water has a pH of 7.8 but the alkalinity is only 18ppm (really low). He claims that, in general, if your water is under 100ppm you don't need to worry about the sparge water pH. Adding lactic acid at this point is overkill. The influence of the pH of your water isn't affecting the running's pH as much the total alkalinity of the water.

I found this surprising. is this common knowledge? I've read of so many people sweating their sparge water pH and adding lactic acid. I suppose if you're a brewer with 150ppm alkalinity, then you should be adding the lactic acid.

 

[Dos_Locos_Brewery]

Since I'm not a chemist, I think I'd need to have alkalinity vs. pH explained again. I usually use just a tiny bit of phosphoric acid, based on an experiment I did a long time ago to see its affect on my water pH. I don't taste the acid at this level, and consider it just one of those quick/cheap/easy things to do as "extra insurance". I agree with you about temperature being more important. The only time I've had tannic beer was when the thermometer was sticking on my hot liquor tank...

 

[jmo88]

Since I'm not a chemist, I think I'd need to have alkalinity vs. pH explained again. I usually use just a tiny bit of phosphoric acid, based on an experiment I did a long time ago to see its affect on my water pH. I don't taste the acid at this level, and consider it just one of those quick/cheap/easy things to do as "extra insurance". I agree with you about temperature being more important. The only time I've had tannic beer was when the thermometer was sticking on my hot liquor tank...

I think many brewers go into the sparge with the mindset that the mash has been accomplished and whatever pH the mash was and whatever the RA was to get it there is done and past. The next step is wrongly thought out as being a clean slate in regards to pH. However, the buffering power of the grains is still present and active, mostly not being affected by the sparge water pH. The total alkalinity of the water however, will begin to affect that buffering power of the grain, just like the mash has done. Sparging with 8-9 pH water doesn't mean that the runnings will start to creep up to that range as you progress with the sparge. That's my understanding.

 

[Bobby_M]

If I were a fly sparger, I might care a little more about sparge pH. In batch sparging, you never have a large quantity of 100% water in contact with the grain. It's always an equilibrium mix between water and whatever wort was locked in the grain structure. Not only that, but you do it so quickly that the higher pH water isn't in contact with the grain long enough to matter.

 

[jmo88]

If I were a fly sparger, I might care a little more about sparge pH. In batch sparging, you never have a large quantity of 100% water in contact with the grain. It's always an equilibrium mix between water and whatever wort was locked in the grain structure. Not only that, but you do it so quickly that the higher pH water isn't in contact with the grain long enough to matter.

Right, this is not a concern for any batch sparger.