GrandFather - big beer help please

Australia & New Zealand Homebrewing Forum

Help Support Australia & New Zealand Homebrewing Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Well-Known Member
Reaction score
Good Morning All.

I'm planning to brew a Christmas Beer with a OG of 1.090/9kg of grain its big beer.

I usually brew beers at about 5% ABV and the only time I've loaded the GF with that sort (8kg+) of grain load I had poor efficiency compared with my usual batch size.. I think it's because the sparge water volume is low.

What's the best way of keeping the efficiency up in the 75%+ region?

Thanks All. Aamcle
I have an idea :-

Sparge 9kg of grain in the normal way. (First runnings)
Pump the first runnings into a bucket.
Add the sparge water to the boiler and recirculate it through the grain.

This should get the sparge water to a consistent concentration of sugars (x g/l) but the grain will still be soaked with that solution.

Is there any advantage in this?

Atb. Aamcle
You would end up with a large pre-boil volume, perhaps you could get the 'second runnings' going with a good boil off (a weaker wort so would not caramelize as much) and then top up with the first runnings as the water level goes down. I'm making this up as I go, so anyone with experience with this chip in with good advice.
Put 4.5 kg of grain into the vessel as per normal for your 5% beers mash and sparge, empty the grain basket and add your next 4.5 kg of grain into the basket and put this into the wort of the first mash, mash and sparge again to bring to required level. If you look up reiterated mash, you may come across the video Chris Colby made using the Grainfather and making a bigger beer using the above method.
You won't get your usual 75% efficiency. Just aim for 60-65% and use a bit more grain.
I did a 8.3kg grain bill on my grainfather and got 1.085 for 23L, if you read the grainfather faq’s it sugessets that with larger grain bills when you mash in add half the grain and let it recirculate for 15 mins to allow it to gelatinise and the add the second half, also I mashed for 2 hours and stirred it 4 times thouroughly during the mash, I also had 100g of rice hulls because I had a small portion of wheat. Crush is really important for large grain bills so avoid any flour.
Good luck [emoji106]
I have done a reiterated mash using my previous system but I didn't get good efficiency it was a lot of trouble and calculating the salts additions for the second mash was impossible.


Latest posts