Water/grain ratio for partial mash?

So I built myself a MLT out of a 10 gallon rubbermaid cooler. Probem is that I'm not doing AG yet. Planning to brew up a partial mash Fat Tire clone tomorrow. I'm only using 3 lb of grain, and I'm a little concerned about the proper ratio of water to grain. I know for mashing AG, somewhere between 1.25-1.5 quarts of water per lb of grain is average. I'm concerned about the low volume of water needed for this partial mash in my (relatively) giant MLT.

Any problems with mashing 3lb of grain in 3-4 gallons of water?

I wouldn't use more than 2qts/lb for the mash and then sparge it after the mash with another 2 qts/lb. Frankly I wouldn't even bother with a 10gallon MLT with 3 pounds of malt. I'd just mash that in a 2 gallon pot.

He's doing the opposite, Bobby. More like 1-1.25 qts per pound.

There's nothing wrong with it per se, but you aren't going to get as good efficiency with a lower ratio. Also, can I ask why you only want to use 3-4 gallons? Are you limited by the size of the mash tun, or is there another reason?

Really wanted to make use of my new MLT, but only have what I need for this Fat Tire clone partial mash.

My mash tun is 10 gallons. Making a 5 gallon batch, but only using 3lb of grain. Didn't want to go much over 3 gallons in the mash to allow enough volume for a decent sparge. Since I was going to do an infusion mash, I've got one shot to get the temp right in the MLT, and the low volume of grain/water in such a big tun (relatively speaking) was my concern.

Guess maybe I'll just park the MLT until I try my first AG batch and go back to my old standby methods for partial mash.

For only 3 lb of grain you are really going to have a hard time maintaining temp in a 10 gallon MLT without something to fill up the dead space.

There is a guy here on HBT that takes a big piece of foam, cuts it to fit inside the MLT, and then wraps it in plastic and sits it on top of his mash when he is mashing smaller volumes.


Really what I would do is adjust the recipe to have more grain in it, maybe even just make it AG and then add extract if you miss your target gravity going into the BK. I mean if you can do a PM you can do an AG just as easily.

weirdboy said:

He's doing the opposite, Bobby. More like 1-1.25 qts per pound.

There's nothing wrong with it per se, but you aren't going to get as good efficiency with a lower ratio. Also, can I ask why you only want to use 3-4 gallons? Are you limited by the size of the mash tun, or is there another reason?

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You need enough water to allow the enzymes to circulate in the mash, but the efficiency goes down as the volume of water goes up. The more water you have the less chance of the enzymes getting to the startch to convert it.

Calder said:

You need enough water to allow the enzymes to circulate in the mash, but the efficiency goes down as the volume of water goes up. The more water you have the less chance of the enzymes getting to the startch to convert it.

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Between 1.5 and 2qt/lb I am pretty sure the efficiency increases. At least, it does in my experience. I haven't really done more than 2qt/lb.

Well, overall, it was a failure this evening. Decided to mash in the new MLT using 3 gallons of water. My problem is that my digital thermometer crapped out on me sometime between heating my water to strike temp and when I tried to monitor the temperature of my mash. Thermometer was reading significantly higher than the actual temperature, so I got scared I overshot my target temperature. Started adding ice to bring the temp down before I realized the problem with my thermometer.

Decided to just let it ride, and while mashing I ran out to Target to get a new thermometer. After an hour mash, I tried my new thermometer out and read a temperature of 134 degrees (my target was 154). Oh well, I proceeded with my boil and added my DME and hops.

Long story short, my target O.G. was 1.05. My measured O.G. was 1.068. So maybe I got a good mash afterall...we'll see how it turns out in a month. In the mean time, I guess I'll start thinking about my first AG batch.