AG problems

[modo]

I've done 2 AG beers and on both times I have had to add water to the fermenter to make up the volume of 23lts.
The 1st time was a simple pilsner of 5kg total grain and was told to do 3lt per kg of water at 66c for 1hr then 5lts for mash out drain then another 3lts per kg for sparge boil for 1hr add hops and was approx. 2lt short.
The 2nd was a robust porter 4.87kg total grain bill and was told to do 12lts[67c] then 6lts for mash out then another 12lts for sparge did another 60min boil ,hops and this time was about 6lt short the mash tun both times didn't have any excess wort in it when I dumped the spent grain.
Next question is how do you find out how your brew efficiency is because beer smith confuses me. Do you take a sample from the first running's chill to 20c and check og or combine 1st and 2nd running's chill and then check.
Any help will be appreciated because still new to this. I have logged all the data so if any more info is needed.

[James L]

Get combined readings to measure efficiency. make sure it is well mixed before taking the measurement. If you get a reading higher than what your beersmiths tells you for the effiency that you have given, you obviously have a better extraction efficiency that what you expected, so you can adjust the effiency on the beersmith to coinside with the OG that you have gotten to work out your percentage. Make sure that you have the gravity for the preboil and not the post boil, as they will be much different (depending on when you take the measurement).

you can find the expected preboil gravity by clicking on the preview brewsheet button near the top.

as for volumes, remember that you lose alot of water in your grain, and equipment, but if you say that most of your water was drained into the kettle, then you might not have done the right calculations to ensure you ahve the right final volume.

1kg of grain will absorb 1L of water. in the mash, so if you ahve 5kg of grain, and you mash with 15, you will only get 10L back. then, if you sparge with the 5+3L/kg =20L, that will give you a total volume of 30L in the kettle, which is fine for the volume you want.

Depending on how vigourous your boil is, you will loose about 20% of the volume of your beer. which still leaves you 24L litres.

I do find that you will never be able to get all that volume out of the kettle and into your fermenter becuase you have all you hot break and hop residue at the bottom.. also depening on your pickup, you may have to leave a couple of litres behind.

that maybe the reason why you only end up with 21L instead of 24L.

The first time i brewed, i was expecting 24L and only got 18... getting the volumes right comes down to knowing where you loose you water during the process, and getting used to your equipment. takes a bit of time...

Now i brew for a final batch volume of 26L becuase i know by the end, i will only end up with about 23L due to loss at certain stages of the process.

I hope that helps.

[warra48]

1kg of grain will absorb 1L of water. in the mash, so if you ahve 5kg of grain, and you mash with 15, you will only get 10L back. then, if you sparge with the 5+3L/kg =20L, that will give you a total volume of 30L in the kettle, which is fine for the volume you want.

I often see this quote of the figure of 1 litre per kg water absorption in the mash. With all due respect, my experience is that it is more like 1.5 litres of water per kg of grain.

In Modo's case, allowing for that, it would have given him about 2.5 litres more into the kettle, which would have given him his target volume.

[Kevnlis]

I think the figure is closer to 850ml per litre from memory.

[James L]

I was only going off what i've read and experienced...

I agree that if he had've added an extra 2.5L of water, he would've got the deisred volume, but i dont believe that the water loss to begin with was due to absorption of 1.5L/kg from the grain. If anything, Modo might not have made allowances for water loss during the boil, or by the volume in the kettle taken up by the hot break and hops debris.. He did say he had to add water to the fermenter, not the kettle. What he should've done was measure the volume in the kettle to ensure that the preboil volume was acheived, then from that we could've worked out whether it was due to excess water absorption by the grain (not achieving preboil volume with the water used), or another step futher down the process (achieving the preboil volume, but not getting the calucated volume in the fermenter).

[modo]

Thank's boys for your responses. If I think I'm short you suggest I add water to the brew kettle prior boiling and not to the fermenter. And when I boil I have a very soft boil all through and stop the clock when I add my chiller in till it reboils and then restart the clock till to 60mins are up.

[warra48]

Yes, what you are saying is basically correct.
If you keep good notes of your brews, you will soon work out what volumes you need to dough in, mash out, and sparge, to give you the required volume pre-boil into your kettle. Then you can measure what you lose to boil off and trub in the kettle. Once you have all that dialled in, it's easy to hit your volumes every time.
As far as the boil is concerned, you do need to have a rolling boil. It doesn't have to be a vigorous or hard boil, but enough to have the wort break the surface so it keeps moving from the bottom of the kettle to the top surface. Don't worry too much about stopping the timing once you drop your IC in. I normally start my boil, and will boil until I have my hot break. I only add my 60 min hops from then, so my average boil length is more like 75 minutes.