Hey murray,
If you are batch sparging, make sure you mix well at end of sacch rest/mashout before the 1st lauter and very well again between the subsequent sparges. I find this alone helps bump up the eff quite abit.
Conventional wisdom supports this approach - the idea being that the stirring helps release the trapped sugars from the grain matter and thus improve efficiency. Yet this approach is also a well known culprit behind cloudy beers. Stirring the mash is good, during the saccharification rest, to ensure a more complete conversion and to help knock out any dough-balls that may have inadvertantly been created during the dough-in stage.
For years I adopted this approach and had nice but always cloudy beers that needed either filtration or PVPP - which was a dead giveaway that I had tannin-protein haze issues caused by stirring during the mash, during mashout and in between batch sparges. The negatively charged PVPP silica gel bonded to the positively charged tannins that caused the tannin-protein haze thus brightening the beer and also quite importantly, not stripping the protein levels out of the beer that help foam and head retention in the glass. Isinglass finings were useless because the positively charged isinglass didn't bond with the +ve tannins and whilst they did help flocc out the cloudy yeast strains, the finings did jack all to the chill haze in the beer.
And then I recently bought a copper sparge ring for the 10 Gallon mashtun;
Straight away, I managed to gain at least 10% extraction efficiency and routinely brew at 80% - without stirring at all...For the first couple of batches, I used the ring and stirred the mash between batches during the sparge and whilst I did gain efficiency, I still had cloudy issues...so I made a conscious decision to do a couple of brews (light and dark beers) and not stir at all after the mash had concluded. Result? No loss of efficiency and very bright beer!
I dough-in and stir well to eliminate dough-ball formation. At the end of the mash, I add my first batch of sparge water via the ring (note the holes are topside on the copper ring so I'm not ramming water down into the grainbed) at mashout temps - the ring just sits on top of the grainbed. I vorlauf then drain without stirring yet keeping the sparge water at least 2 inches above the grainbed, stop the sparge, add more hot sparge water for the second batch - still no stirring because I have a great filter bed now and I don't want to disturb it and I have no channelling since the sparge liquor is always above the untouched grainbed surface - drain the mashtun (knowing your sparge volumes is important here because you don't want to oversparge the mash and pull tons of tannins into the brew kettle) and start the boil.
So, my experience is that yes, you can gain efficiency by regularly stirring the mash, but I get much brighter beers (and still have excellent conversion efficiency) by trying not to trash my grainbed filter through stirring in between batches -
the key is to keep at least a couple of inches of sparge water above the grainbed throughout the sparge.
I've also been able to do a "mashout single batch sparge" - where I add the entire volume of the sparge to the mashtun, wait 5 mins, vorlauf, and just let the mashtun drain in one go - having a 10 Gallon mashtun helps!!
Cheers,
TL
