Back to Shopping at

Thin Mash with Light Sparge, or Opposite?

What’s the recommendation? Which will result in the best real-world efficiency? Should I (A) perform a thin mash (1.50+ qt/lb) and have a relatively small sparge (~1.5 gallons), or should I do the opposite: (B) perform a normal/thick mash (1.25- qt/lb) and have a normal-ish sparge (3+ gal)?


I am not certain since I’ve never done specific tests on the subject, but a fine crush along with a thin mash (1.5 - 2qrt/lb) and a normal sparge get me an average efficiency between 75-85%.

If I did a 1.5qt/lb mash, I’d be sparging with only about 1 gallon, though… Just to clarify, if I did a thin mash with a “normal” sparge (~3 gallons), I’d end up with about 2 gallons extra I’d need to boil off.

This is for 17 lbs of grain/hulls, so a “thin” mash at 1.5+ qt/lb is a lot of liquid in the mashtun.

Conventional wisdom say equal runnings. I’ve found there’s little difference though, like within 5%.

Like Lenny said.

If you really want to get the highest efficiency, try fly sparging. However, you’ll spend a lot of time dribbling your sparge through just to get a few extra %, and if your set-up isn’t designed well for fly you will actually loose efficiency. If you want to keep to batch sparging, try for three runnings (mash plus two sparges), calculated to provide equal volumes of runnings for each batch. But just like fly sparging, that is a lot of work to get a small boost in efficiency.

The one technique I’ve used that really seems to boost efficiency is decoction mashing. You can get a 5-10% bump in efficiency by doing that.

I’ve seen this with decoction, but I generally find it results in a less fermentable wort too. So that extra stuff doesn’t all ferment out. Depends on what you want of course.

I hadn’t realized that. So it would make sense then for a Bohemian Pilsner, but not a German one?

Yeah I think you can depend on it enough to use it as a tool to reach a certain FG/mouthfeel. And if you think it gives a certain flavor profile you can always adjust the grist to compensate, or maybe mash longer to reduce the effect.

There is no way to tell, it will vary from system to system.
I get best efficiency if I keep mash and sparge equal.

And the “equal runnings” concept means you calculate the amount of water the grain will absorb and hold onto, then subtract that from your intended preboil volume, then divide what left by two. For mashing you add the absorbed volume plus the runnings volume, and for the sparge just the runnings volume.

On a guess I am usually splitting it by 3.5 to 4g for each

One variation on this that can help, especially if you are brewing a lower gravity beer or one that you intend to boil for a long time, would be to divide the amount you calculate for the mash volume and add however much you need to get the mash thickness you want, then add the rest at high temperature just before you drain the tun. Sort-of like a mash-out, but not really. All this does is allows you to do a thick mash and still get equal runnings.

True, this works. You can also mash with the full amount even though it might be over 2qt/lb. I’ve found this doesn’t affect conversion, otehr than taking a little longer.

After a lot of trial and some error, I have gone with mashes in the range of 7 gallons for a 10.5 gallon batch of beer with approximately 18 pounds of grist (I make a lot of light lagers). I will run about a gallon and a half into the mash at the end of the mash (not mashing out, really, but usually raising the mash temp slightly); then I batch sparge with 6.5 gallons of sparge water (15 gallons total), collecting on average about 12.75 gallons, which I boil down to 11 or so with a 90 minute boil (this means I start with 15 gallons, which is handily three 5 gallon jugs of water - hard to mess that up, even after a late night with the boys the night before brewing).

For a range of 16-22 pounds of grain (my typical 10 gallon batch size of grist), I am pretty much okay with the same set up, often not adjusting for the high or low end of the range (just boiling longer, if I want to reach a specific gravity). If I am a bit under in volume, I am typically a little higher on OG, so I will occasionally add a little water to top up the batch in the fermenter when needed (or just live with the lower volume/stronger beer!) After fermenting, I typically yield right around 10.5 gallons (or a little more), which allows me to fill a 2 liter soda bottle as a “green beer tester” by quickly chilling and force carbonating it.

If I am doing a specific recipe from another brewer, I will do the proper volume calculations, but for run of the mill “house lagers”, this quick and dirty system has been working fine for my 10 gallon batches.


Back to Shopping at