Hop Calculations In Smaller Boils

[redmactruck]

Just wishing to get advice re hop calculations to smaller boil sizes (eg 4 litres ) to finally make up 23 litres. I am planning a Bohemian Plisener (Pilsner Urquell Clone)

3 kg Briess Pilsner DME
Czech Saaz hop pellets (AA 2.5% )
Wyeast 2001 Pilsener Urquell yeasts

I intend on using 0.5 kg DME in 4 litres of water to get boil gravity of 1.047 which is close the final gravity @ 23 litre with the rest of DME added
I have plugged my figures into hbd.org/recipator, brew365 ibu calculator, Beer Smith and getting a little confused

For a 23 litre batch with 23 litre boil the final gravity is right at 1.047 and hop schedule 114g@ 60mins / 21 g @ 40min /21g @ 25mins gives me a IBU of 40 -- exactly what i am looking for =====> BUT I have a small stockpotl (6-8 litre boil max with head space)

For a 4 litre boil with all the extract added would obviously bring the boil gravity up and therefore hop utilisation down - so I tricked the calc by adding the final batch size was 4 litres with only 0.5 kg DME added -- the final gravity was 1.047
but with this hop schedule as above the IBU was 220-240 depending on which software program

Does this mean when I finally add the rest of the DME and water up to 23 litres the IBU will "diluted" from 220 to 40????

Do I need to reduce the hops by ratio of 4/23?


Any help in this regard would appreciated.

 

[pimpsqueak]

I plugged your ingredients into beersmith and got an OG estimate of 1.047 (assuming potential SG of pilsener malt is 1.043).
Using your hop schedule and a 4l boil, I get an IBU of 38.5 in a 23l batch.

So yeah, it looks like it dilutes the IBU from 220 to 40 when you dump it into 20 litres of water (the water is approx 5 x the volume of wort added, so divided by approx 5 makes sense).
BTW, not long ago someone pointed out to me the "add after boil" checkbox in the window that comes up when you double click your extract. Using that function and setting your boil size to 4l will give you accurate figures.
Just make an entry for 500g dme for the boil and another entry for the remaining 2.5kg and check the add after boil box.

 

[redmactruck]

I plugged your ingredients into beersmith and got an OG estimate of 1.047 (assuming potential SG of pilsener malt is 1.043).
Using your hop schedule and a 4l boil, I get an IBU of 38.5 in a 23l batch.

So yeah, it looks like it dilutes the IBU from 220 to 40 when you dump it into 20 litres of water (the water is approx 5 x the volume of wort added, so divided by approx 5 makes sense).
BTW, not long ago someone pointed out to me the "add after boil" checkbox in the window that comes up when you double click your extract. Using that function and setting your boil size to 4l will give you accurate figures.
Just make an entry for 500g dme for the boil and another entry for the remaining 2.5kg and check the add after boil box.


Thankyou for your reply - I will try this tonight when finish work -- :drinks: you were talking about "beersmith" where there is this function for adding DME after boil== yes?

 

[pimpsqueak]

I plugged your ingredients into beersmith and got an OG estimate of 1.047 (assuming potential SG of pilsener malt is 1.043).
Using your hop schedule and a 4l boil, I get an IBU of 38.5 in a 23l batch.

So yeah, it looks like it dilutes the IBU from 220 to 40 when you dump it into 20 litres of water (the water is approx 5 x the volume of wort added, so divided by approx 5 makes sense).
BTW, not long ago someone pointed out to me the "add after boil" checkbox in the window that comes up when you double click your extract. Using that function and setting your boil size to 4l will give you accurate figures.
Just make an entry for 500g dme for the boil and another entry for the remaining 2.5kg and check the add after boil box.


Thankyou for your reply - I will try this tonight when finish work -- :drinks: you were talking about "beersmith" where there is this function for adding DME after boil== yes?

Yep, it's in Beersmith.
Make an entry for some dme then double click on it to see it's properties. You will see the check box about halfway down the page.

 

[redmactruck]

Yep, it's in Beersmith.
Make an entry for some dme then double click on it to see it's properties. You will see the check box about halfway down the page.

all good, worked it out, thanks for the tip -- I''l let you know how it goes