Bugs when using goal function

[Craigerrr]

Yesterday I copied a recipe to essentially take a 4.3% hazy, and crank it up to 6%.

1) When I used the goal function and entered the new ABV I entered 6%, but it only adjusted it to 5.4%. I then used the goal function to change the OG, and played with that to get it where I wanted it.

2) Looking at the new recipe today to see what ingredients I may need to buy to be able to brew, I notice that the rice hulls were at 0.02 pounds. They were 1.9 pounds in the source recipe.

3) SRM: source recipe, 3.73 new recipe 3.96 (no big deal)
pH: source recipe 5.35, new recipe 5.66 (kind of expected the water agents to be scaled as well, had to adjust water amounts as well)

 

[Pricelessbrewing]

Thanks for the report @Craigerrr, could you post or message me the recipe you're using so I can investigate?

There's an issue where when using the goal, the percentages change to % of sugar contributions which take PPG into account, instead of % by weight. I'm hoping that's the case here for 1 and 2.

For 3, since the fermentables, OG, and mash chemistry/water agents are not linear and are related in pretty complicated ways I don't think this is something that will happen any time soon. You'll need to update the salts/acids after changing the grain bill in anyway. If you think it needs to be conveyed more clearly, we could look at adding the pH into the goal seek window so it's communicated more clearly.

 

[Craigerrr]

Thanks Priceless, hope this helps explain what I am getting

Here is the source recipe
https://www.brewersfriend.com/homebrew/recipe/view/957937/low-speed-chase

Here it is copied, then changing Maris Otter to 2 Row, had to increase the weight to gt same OG.
https://www.brewersfriend.com/homebrew/recipe/view/1010871/lsc-test

Here is LSC-Test, copied again to use the goal function for adjusting ABV up to 6.0%
This is where it dropped the rice hulls, and it only adjusted the ABV up to 5.42%
https://www.brewersfriend.com/homebrew/recipe/view/1010872/lsc-test2

I also copied LSC Test to LST Test3, and tried using the goal to up the OG to 1058, the result was 1052
https://www.brewersfriend.com/homebrew/recipe/view/1010874/lsc-test3

No worries on #3, adjusting mash water, and water agents

 

[Craigerrr]

I also noticed that it changed the water source from RO to Cambridge, which is where the pH change came in.

 

[Pricelessbrewing]

Alright I'm 90% sure that what's happening is the same issue as noted above. The rice hulls are being dropped because the PPG is zero, since the goal feature is assuming the grain bill % is by pts (or equivalently by % sugar contribution) instead of % weight, it's not working correctly. Most notably this will have issues for adjuncts, rice hulls, and very dark roasted malts where the PPG is far off the total recipe average.

It's hard to tell if it's 100% covering all the issues here since I'm seeing several results that don't line up with my expectations in this one scenario.

I'm adding this forum thread to the existing ticket and giving it a bump.

Those recipes weren't shared publicly, so I opened them in your account and copied them with priceless in the name. All LSC test recipes were left in tact other than my priceless copies, feel free to delete those if you'd like.

 

[Craigerrr]

Thank you, and sorry about the permission error

 

[Pricelessbrewing]

Thank you, and sorry about the permission error

No worries, keep letting us know any issues you find or any suggestions you have on where we can improve.