water quantities, advise please

[Fien397]

Hi everyone. ive just finished doing my first all grain brew, all went relatively smoothly, but its raised a few questions. firstly, if im fly sparging, at what point should i stop sparging? should i stop once ive got enough wort for the boil, ie 28L or should i stop at a specific gravity, and then top up with water? im using jims stock recipe by the way, and used 2.8g of mash water as directed. also if for some reason im short of the total volume i wanted at the end of the boil, is it too late to top up

[Horden Hillbilly]

Hi everyone. ive just finished doing my first all grain brew, all went relatively smoothly, but its raised a few questions. firstly, if im fly sparging, at what point should i stop sparging? should i stop once ive got enough wort for the boil, ie 28L or should i stop at a specific gravity, and then top up with water? im using jims stock recipe by the way, and used 2.8g of mash water as directed. also if for some reason im short of the total volume i wanted at the end of the boil, is it too late to top up

Firstly, well done on your 1st ag brew & I am sure that you will be delighted with the resulting brew.

Regarding fly sparging, as long as your final runnings from your mash tun are 1006 or above, you will be ok. Any lower than this & you run the risk of extracting "undesirables" from the mash, To check this, on your next ag brew collect the last runnings from your mash tun, cool it to 20c & take a hydrometer reading.

Regarding topping up if you are short, I do this myself using filtered water. I tend to try to slightly undershoot rather than have too much wort collected. When you have done a few brews & get to know your system, you will be end up with near enough the amount of wort you require & you will only need a small amount of top up water.

[Madbrewer]

I'd stop when you get to your intended boil volume! Not wanting to confuse you I thought I would impart some advice that was recently imparted to me. The North Hants brewers had got toegther for a tasting and what I thought was a beer that needed a little mellowing, turned out to be one that I had indeed oversparged thus getting some of those undesired flavours mentioned by Hornden.

The advice given at the time was to try and be less efficient. Though it costs more per pint, it would definetely be a good investment if it made the beer much better tasting. So Basically I stopped fly sparging in favour of batch sparging and was tought how to batch sparge ineffeciently. Despite 1.006 being the 'harsh' point, the other school of thought goes that the 'better' tasting substances get released earlier on. In earlier periods of brewing history people have even brewed without sparging at all. So to answer your question, I would really stop when you get to your desired boil volume whatever.

---- The remainder of this post is a little geeky & you don't NEED to do it ----

The science of 'how much' is based on sugar points. Basically a 'point' being one unit of gravity per litre. There's an 'LDK' figure for each malt & pale malt is around 296. Which means it will give 296 sugar points per kilo (IF you got 100% efficiency.) As I now AIM for 73% the maths goes like this 25 'litres' * 44 (for 1.044) = 1100. But that's based on 100% efficiency so I need to get 1506 sugar points.

1506 points / 296 = 5,080g of Pale Malt.

Basically by taking gravity readings of your obtained wort you can calculate how many sugar points you have and you can stop when you have obtained the sugar points you require.


Here's the thesis that SteveD kindly wrote for me :-
viewtopic.php?t=11841

[Fien397]

Thanks for the info guys, thats cleared things up