Grain/Water Ratio?

Could someone give me some advise on how critical the grain/water ratio is for mashing?

I'd always been told the slurry needed to be thick to get high extractions. But nowadays everyones' going with RIMs/HERMs systems which need more more water to operate effectively.

Was low water-ratio mashing simply a myth dumped on me or is there any substance to this?

I use 1.25 qt/lb of grain. I batch sparge (twice).

http://www.howtobrew.com/section3/index.html

I see Palmer says it is better to have a high- rather than low-water ratio. http://www.howtobrew.com/section3/chapter14-6.html.

I run 1.5 or 1.75 qt:lbs depending on how I am approaching my mash. I get good efficiency, high 70's on my lighter beers and into the 80's with some of my darker ones.

I've always used a ratio of 1.25 and have had good results. High 70s/low 80s efficiencies, usually.

To anyone researching just reading this thread, please read this excerpt from Palmer:

"A thinner mash of >2 quarts of water per pound of grain dilutes the relative concentration of the enzymes, slowing the conversion, but ultimately leads to a more fermentable mash because the enzymes are not inhibited by a high concentration of sugars. A stiff mash of <1.25 quarts of water per pound is better for protein breakdown, and results in a faster overall starch conversion, but the resultant sugars are less fermentable and will result in a sweeter, maltier beer."

If Palmer's right - go for the more dilute mix and getter a better extraction.

Thanks to all who helped.

Yeah, with my 1.25 qt/lb I'm getting 75-80% efficiency. I buy my grains from BrewmastersWarehouse and have them mill my grain and others swear by their milling (I don't really have a comparison). My last two batches were both 10 gal batches with 18+ lb of grain, in my 10gal MLT I have no choice but to run 1.25 - which I did even with 5 gal batches and still get my above mentioned efficiency (75-80%).

There's no difference in attenuation between thick and thin mashes. Resident brew science guru Kaiser did the tests a while ago.

No difference in attenuation perhaps, but the Kaiser test concludes ".. thinner mashes perform better and allow for better extraction of the grain."

jkarp said:

There's no difference in attenuation between thick and thin mashes. Resident brew science guru Kaiser did the tests a while ago.

Click to expand...

Based on what I have observed, I would agree with Kaiser's conclusions within the limits that he tested.
Going outside those limits however, I think that there can be a considerable difference. I usually brew British Ales, and they are traditionally mashed at 1 qt / lb (outside of Kaiser's parameters).
I've tried 1 qt per lb, and mashing at 150 - 152. Results were excellent.
I tried the same recipes at 1.25 qt / lb. This resulted in a very thin tasting beer (by British standards) with greater attenuation. Sorry, but I have lost the records, and I can't remember what the attenuation difference was.
I tried mashing at 156F and 1.25 qts / lb, and the attenuation reduced, but there were severe off flavors. Again the records have been lost.
In support of this, I quote Greg Noonan New Brewing Lager Beer (page 140 in my copy)
"Mash thickness also affects the fermentability of the wort. A thick mash (less than three-tenths of a gallon of water per pound of malt), induces the greatest overall extraction. A much thinner mash increases the proportion of maltose, and thus wort attenuation."

and Ray Daniels Designing Great Beers Page 15 in my copy, table 3.1
"158F mash of 2 row malt, Flavor notes O3"
were O indicates off flavors, and 3 indicates strong to overwhelming

-a.

I use 1 qt/lb for English beers and 1.25 for all else, and get great efficiency with both.