Using sugar and getting correct gravities.

[Erik the Anglophile]

So I have switched up from 10L to 12L batches for my normal strenght beers, and discovered that the amount of sparge water to subtract from beersmith suggested amount from absorption rate is not really linear.
Ended up with a little too much wort and pre boil SG of .34 instead of .37, not right but no big deal, but after adding the calculated amount of invert and boiling I ended up with an OG of .47 instead of .54. So something seems a little off with the sugar since the initial difference shouldnt warrant that much of a drop in the OG.
Could it be that the too much wort made the sugar amount become too low to raise the gravity to my desired level or could it be it simply does not raise it as much as beersmith thinks?

 

[Miraculix]

When did you add the sugar? You are 100% sure that it was evenly mixed and your sample wasn't just off from the average?

 

[Erik the Anglophile]

I added it as the wort was starting to boil so it boiled for 90 min, I think it was evenly mixed by the time I tested OG.

 

[Erik the Anglophile]

I am starting to think it is several factors contributing to this, lower grain absorption than BS is set to leads to a larger, more diluted pre boil wort wich leads to a little more invert actually needed and all this then builds up to a larger volume in to the fermenter and lower OG than predicted. I have to get my actual grain absorption correct, I got the amount of sparge water to subtract from the estimate right when I made slightly smaller batches.

 

[Miraculix]

Probably. Dialing in a new system can be a pain. I just went through the same struggle. I now have numbers that work for my normal (Americans would say low) strength beers, they don't really reflect reality, but they lead to predictable outcomes, that's what counts.

I actually have no idea if my kettle is actually 17 l big or if I really have 70% efficiency, but with these numbers, I can predict my og reasonably well

 

[Erik the Anglophile]

I still use the same system, just upped the batch sizes a bit, but I guess all the variables are not exactly linear.
My efficiency has been pretty spot on at 75% for.45 to about.65 so I can trust that, I just gotta get the variables to calculate how much water I actually need correct.

 

[moorejl57]

My last small 8l batch came out a little dilute as well. I had added extra strike water to get the level high enough for my sous vide circulator and then forgot to remove 2l before doughing in. I had to do a 90 min boil to get it back to where I had targeted.

You could always mash a little thicker and then dilute back to target after sparging. I would be surprised if grain absorption is not very close to linear for the same grain mix.

 

[Erik the Anglophile]

Yeah I guess the absorption value is pretty linear as long as you use a similair water/grist ratio, gonna keep going at 2.6-2.7 liter/kg for my normal gravity and high gravity beer with sugar/invert added.
Next time a brew I'll make a slightly too small wort before boil, top it up and treat sparge + top up water as total sparge water amount in BS and tinker with the absorption factor until the suggested amount of sparge water matches the amount I actually used. My efficiency has been pretty correct so my gravities should be right after top up.
That should give me a number I could somewhat trust for most beers except maybe high gravity beer with only malt in the bill.

 

[Holden Caulfield]

So I have switched up from 10L to 12L batches for my normal strenght beers, and discovered that the amount of sparge water to subtract from beersmith suggested amount from absorption rate is not really linear.

^Assuming you have mashtun dead space - this is probably due to spreading the mashtun deadspace loss over more wort. Grain absorption stays the same, its just that you do not leave as much wort behind relative to wort in the mashtun.

Ended up with a little too much wort and pre boil SG of .34 instead of .37, not right but no big deal, but after adding the calculated amount of invert and boiling I ended up with an OG of .47 instead of .54. So something seems a little off with the sugar since the initial difference shouldnt warrant that much of a drop in the OG.

^The only way to know for sure what happened is to determine the wort points that went into the boil kettle and the wort points that you ended up with. If the points do not balance then something is off with measurement and it is impossible to determine exactly what happened. If the points balance, then you will know if this issue is due to extra volumes, too few points made it into the boil kettle (lower than expected mash efficiency or not enough grain), or too little sugar. What is your preboil volume, post boil volume, and how much invert sugar did you add?

 

[Erik the Anglophile]

^Assuming you have mashtun dead space - this is probably due to spreading the mashtun deadspace loss over more wort. Grain absorption stays the same, its just that you do not leave as much wort behind relative to wort in the mashtun.


^The only way to know for sure what happened is to determine the wort points that went into the boil kettle and the wort points that you ended up with. If the points do not balance then something is off with measurement and it is impossible to determine exactly what happened. If the points balance, then you will know if this issue is due to extra volumes, too few points made it into the boil kettle (lower than expected mash efficiency or not enough grain), or too little sugar. What is your preboil volume, post boil volume, and how much invert sugar did you add?

I use a 14L cooler tun to mash in, then I transfer the mash to a bucket with lots of small holes in the bottom placed in an ordinary bucket with a spigot, drain out the first runnings and fill up with my sparge water, stir let sit and then empty, I can lift up the false bottom bucket to pour out the last bit so deadspace losses are non existant.
When I was doing 11L post boil volume batches I simply subtracted 0.7L from BS suggested amount of sparge water, and always hit my volumes and gravities pretty much spot on.
This lead me to believe the problem is with the standard setting of grain absorption in BS, it overestimates how much water the malt will absorb in the mash.
This could also explain why my OG came out so low, a wort volume that was larger and less concentrated than the wort the amount of invert was calculated on is gonna need a new amount of invert to match the gravity points it is supposed to yield.
I'm just speculating though but it feels plausible.

 

[Holden Caulfield]

This could also explain why my OG came out so low, a wort volume that was larger and less concentrated than the wort the amount of invert was calculated on is gonna need a new amount of invert to match the gravity points it is supposed to yield.

^Yes, assuming your measurements of gravity and volume are correct, there are only two factors that impact gravity - amount of sugar that enters the boil kettle and the amount of water left in the kettle after boiling. Your beer plan can go wrong in many places...

• Grain bill & pounds not measured correctly
• Expected mash efficiency differs from actual
• Wort collected and adjusted from lautering differs from preboil target
• Kettle additions pounds differs from plan and their impact to volume not factored
• Boil rate differs from actual
• Post boil volume differs from target due to preboil volume being off and/or boil rate differing from plan

It is possible for the errors above to cancel each other out so that your target gravity is achieved - usually with something else being off like volumes and IBUs

The invert sugar calculation is just a formula that will provide a number that is just as good or bad as the input data. The only way you will ever know what actually happened and make adjustments to your recipes and process is to measure your preboil and postboil volumes and gravities and determines wort points (which is very easy) otherwise the issue could be anywhere in your system and you may end up breaking something that is not broken and chasing your tail.