Boil Volume vs IBUs

[dttk0009]

I'm making my 3rd batch this coming week and it's going to be a relatively simple recipe. My 2nd one I largely miscalculated and added way too much malt, so now I've got a pseudo porter instead of an amber ale. Not really all that bad, just not what I expected.

Anyhow, on to my dilemma. I've looked around the forum and found a couple of threads pertaining to the same subject matter I'm about to present, but they didn't really offer 100% clarification so I figure I'd ask again. I want to brew a Hefe-Weizen and will be using the following recipe:

1.37kg Wheat Extract (Dry)
1.06kg Light Malt Extract (Dry)
0.21kg Carafoam
??g Liberty hops (60m)
Wyeast Labs Bavarian Wheat Yeast #3056
20L batch

This time I'm trying to be as meticulous as possible to avoid any miscalculations and have started using Beer Smith to help. As I'm still quite the noob, I'm sticking to stovetop brewing with BIAB for mashing until I get the feel for creating recipes and executing them.

I noticed that when I change my boil volume to 10L, the number of IBUs I get drops somewhat drastically. I want to achieve 10IBU with this recipe. Below are the amounts according to boil volume:

10L (what I'll be using) - 28.89g for 10IBU
20L - 19.31g for 10IBU

Is it really that drastic of a difference? I'm a bit worried now because I don't want to over-hop this beer. The solution I've read so far is to add the DME at the end of the boil to improve hop utilization during the boil. If I do this, how much should I use and which formula should I trust?

Any input would be really appreciated. Thanks!

 

[dcp27]

The solution I've read so far is to add the DME at the end of the boil to improve hop utilization during the boil. If I do this, how much should I use and which formula should I trust?

In BS, if you double-click on the extracts there's an option to add them late in the boil so it can calculate the change for you.

Also, the difference in hopping shouldn't have been that big of a difference, but close. Its about a 20% change. Either way, there's not a worry of over-hopping here. With those amounts you may not even be able to tell the difference.

 

[pkeeler]

Why are you mashing? There is nothing to mash that I can see in the recipe.

I don't think you can lower the batch size without reducing the extract amounts. If you put ~2.5 kg of dry extract in 10L, you will get a beer with an OG of 1.093. Not really a hefeweizen at all. Unless you top off to 20L. If that is what you plan to do, then ignore this paragraph LOL

 

[Wyrmwood]

Use brewtarget. You can enter the ingredients and tune your timings and amounts to achieve a specific IBU. I assume you can do the same with Beer Smith, I've just never used it.

 

[erikpete18]

Yeah, Beersmith should be able to change some of the extract to a late addition and then it will recalculate the IBUs for you. I always just try to keep the majority of the boil at about the gravity of the beer, so if you are doing a half boil use half the extract as a late addition. Either the wheat or light could be moved. Not sure about wheat dry extract, but wheat liquid extract always turned out a little darker than I wanted, so I'd probably pick that as the late one just to keep some of the darkening down, but you'd be safe either way.

 

[dttk0009]

Thanks for the helpful responses! I found the little option for late boiling extracts and it works out perfectly in BS. As recommended, I configured it to calculate the IBUs if I add the wheat DME with 15 minutes left, and it gives me roughly 20g of hops for 10IBU. Looks a lot better now.