Proper Sparging Method

[sideshow_ben]

I built a new mash tun over the last week and figured I would try making my own sparge arm too. Today I tried fly sparging with it, and realized that I have two quite-different methods in mind:

1. Add just about enough sparge water to so the mash+sparge water equals the total needed. At the end of the sparge, almost all the water will be drained from the lauter tun. During some of the sparge, the level stays 1-2 in above the grain bed, but not for the whole process. This only takes a few gallons of sparge water (roughly half the total amount in the mash tun at mash out).

2. Keep adding sparge water to maintain a constant level in the lauter tun throughout the entire sparge. My idea here is that the water level should always remain 1-2 in above the grain bed, so the constant addition of fresh water pushes all the sugar out. This takes many, many gallons of sparge water (roughly the mash and mash-out volume plus the sparge volume called for in step 1).

I thought No. 2 was the right way, and ended up having to heat about 6 gallons of sparge water. My efficiency was lousy, but I think it was because of poor temperature control and unevenly mixed grains. I started looking into reasons why my efficiency was horrible, and found method No. 1 instead. I thought the water level was supposed to be kept above the grain bed during the whole sparge, so I'm confused which is the right (or better) way.

-ben

 

[Bobby_M]

Both ways are done and I don't think anyone has hard data on which is better (does anyone?). I understand how sparging works and the only detriment I can figure to letting it run dry is that the weight of the unsuspended grain at the top will start compacting the lower half. It MAY encourage channeling. You may want to try a compromise. If it takes 6 gallons to keep the water over the grain until the end, go with 4 gallons so that only the top inch or two of grain goes dry by the end.

 

[30burps]

Both ways are done and I don't think anyone has hard data on which is better (does anyone?). I understand how sparging works and the only detriment I can figure to letting it run dry is that the weight of the unsuspended grain at the top will start compacting the lower half. It MAY encourage channeling. You may want to try a compromise. If it takes 6 gallons to keep the water over the grain until the end, go with 4 gallons so that only the top inch or two of grain goes dry by the end.

The compromise is exactly what I've been doing and have had great results. I dough-in at 1.2ish-q/gal, mashout with 1.5 to 2.5 gallons of boiling depending on grain bill then heat up ~5 gallons of sparge. My setup requires 8 gallons in order to hit 5.5 after a 90 minute boil, so I cut off the sparge with about a gallon or so to go and the top maybe third to half of the grain bed goes dry. Since I've switched to this method I've nailed my efficiency at 78-80 over 6 batches now.

Also, it is noteworthy that I make sure that my sparge is nice and slow. I shoot for collecting 1g per 10min so that it takes me 80min to get my pre-boil volume.

 

[ajf]

I don't use either method, or the compromise suggested by Bobby.
The problem with pre-calculating the amount of sparge water and assuming that the sparge will run to completion, is that you will almost certainly end up over sparging.
I prepare as much sparge water as for your method 2, but I monitor the gravity of the runnings (using a refractometer) as the sparge progresses. With my current equipment (using a 10g MLT), the runnings drop to about 2.5 brix (approx 1.010) a long time before I have collected the required pre-boil volume. With my old equipment (using a 5g MLT), I could collect considerably more before the gravity of the runnings dropped that far, but even so, I usually had to add some top-off water to the kettle to prevent oversparging.

-a.

 

[Bobby_M]

ajf, wouldn't mashing a little thinner or using more mashout volume fix your problem. It would avoid running off that high gravity wort early in the sparge and push off the low gravity runnings to later. I guess having a pH meter would be the best way of preventing oversparge because it can happen in wort above 1.010. Depending on your sparge water chem, you may even be able to sparge to a lower gravity before the pH goes off.

 

[ajf]

I don't consider my current method as a problem that needs fixing. I agree that measuring the pH, rather than the gravity of the runnings makes sense, but I can get the gravity quickly and easily with the refractometer, while I have no way to get a quick accurate pH reading, and my sparge water is always acidified except when making a stout (which I do less than once per year). By the time that the gravity drops to 1.010, there really isn't any point in sparging any further as the amount of extra sugars extracted would be so small that it would make no measurable difference.

-a.