I am a few all-grain brews in using the Robobrew (poor mans Grainfather) and they have actually turned out great!. One thing I haven't been able to figure out though is how to improve efficiency. People say not to worry about it, but it is frustrating having 5.5 - 7kg of grain and then still only producing a 4.5-5.5% abv beer. Also becomes an economical issue - spending more on grain than necessary.

So far I have had the stores mill it for me. I will look to get my own grain mill, however would like to ensure I am doing all I can without it first. I have included some examples below - all at Single step mash - 67c for 60 min, recirculate the mash using pump, mash out at 76c for 10 min, approx 20 Litres water + 10-14L fly sparge, standard 60 min boil. Please let me know if any more detail required:

**Brew 1**
Marris Otter Pale 5kg, 
Flaked Oats - 500g
OG: 1.049
Using brewers friend calculators this equates to ~68% mash efficiency

**Brew 2**
American Ale malt (Gladfield) - 5.50 kg
OG: 1.053
Mash efficiency: 73%

**Brew 3**
Marris Otter Pale 5kg, 
Flaked Oats - 500g, 
Dark Chocolate - 500g
Roast Barley - 500g
Dark Crystal - 250g
OG: 1.055
Mash efficiency: 66%

How can I improve efficiency?

Things tried so far (which have now improved efficiency): 1. stirring the mash regularly 2. 2 step mash at 62c and 66c


  • I always get poor efficency with single infusion mashes. Try a step infusion or decoction mash.
    – Robert
    Sep 5, 2018 at 16:25
  • I wouldn't complain too much about anything above 65. I have trouble getting much higher than 70 because of the heel in my brew kettle. Another culprit could be low mash temperatures. Do you perform a starch test before mashing out?
    – mreff555
    Sep 8, 2018 at 19:37

2 Answers 2


Forget about the mash timer. A mash is done when there's no more starch.

The finer the grain crush, the more mash efficiency you will get. Up until it's so fine that it gets stuck. Finding that balance on a system is usually trial and error. Though in your case you may find other robobrew users and follow thier suggestions.

Yes pH and water chemistry play a big roll in mash effeciency, but only to the extent that ideal levels save time as the enzymes can work more efficiently.

So more time will compensate for other short commings in a mash. Use an iodine test every 20 min to know when the mash has converted all available starches.

  • Not if you use BIAB you can turn the malt into flour and never a stuck mash Sep 5, 2018 at 16:24
  • @farmersteve well about 20% can go flour. Or it just stays in the bag without a lot of squeezing, which is the biab equivalent to a stick sparge. Sep 5, 2018 at 16:25
  • I don't understand that. If the flour is floating in the mash and it converts to sugar isn't soluble in the water? Sep 5, 2018 at 16:31
  • @farmersteve then your talking like .75g/lb water grist ratio Sep 5, 2018 at 16:33
  • Full volume mash whatever the ratio is about 3 quarts per pound of grain so I guess around .75 g/lb Sep 5, 2018 at 17:28

Water chemistry, particularly mash pH, can have a large effect on efficiency. My first step would be to check the pH of the mash and make sure you're in the 5.2-5.8 range (ideally closer to the low end of that range). It's also important to measure volume correctly, have you calibrated whatever you use to measure out water?

  • I have not measured the PH, I will check and see on the next brew - Thanks! The robobrew has volume markings on the side which I have checked for accuracy. I don't really measure out the sparge water per se, just top up to the right volume.
    – W4K1NG
    Sep 5, 2018 at 9:19
  • I've increased my mash efficiency in single infusion by controlling pH and also increasing the water grain ratio, now near 3l/kg.
    – rondonctba
    Sep 5, 2018 at 18:31

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