OG way off 🤷‍♂️

[Red Raven Brewery]

Hey,
So a few weeks ago I brewed a Czech pilsner and my post mash was roughly +3 on what it should be but post boil was -7 on where it should.have been.

Then today I've brewed a witbeir and despite an entirely different AIO system it was +9 on post mast but -10 on post boil.

I can't figure it out, what am I missing? Two different AIO systems but a similar problem

 

[Agentgonzo]

How are you measuring the gravity? Hydrometer? Refractometer? At what temperature?

 

[RoomWithABrew]

Also how sure are you on your volumes?

 

[Red Raven Brewery]

How are you measuring the gravity? Hydrometer? Refractometer? At what temperature?

Both and they seem to be bother telling the same story. 20° or there abouts but even when I've taken readings on the hydrometer at higher temps and used a correction calc it's been the same when cooled.
I also have a rapt pill that has only give a different reading by +1

Also how sure are you on your volumes?

I'm using the markings on vessels. I haven't tested them myself to see how spot on but they seem about right

 

[RoomWithABrew]

Both and they seem to be bother telling the same story. 20° or there abouts but even when I've taken readings on the hydrometer at higher temps and used a correction calc it's been the same when cooled.
I also have a rapt pill that has only give a different reading by +1

I'm using the markings on vessels. I haven't tested them myself to see how spot on but they seem about right

Are you adjusting those volumes for temperature?

 

[foxy]

Hey,
So a few weeks ago I brewed a Czech pilsner and my post mash was roughly +3 on what it should be but post boil was -7 on where it should.have been.

Then today I've brewed a witbeir and despite an entirely different AIO system it was +9 on post mast but -10 on post boil.

I can't figure it out, what am I missing? Two different AIO systems but a similar problem

To get an accurate reading post mash you really need to give it a good stir, sugar in the wort is dense and will settle at the bottom of the kettle.

 

[Red Raven Brewery]

Are you adjusting those volumes for temperature?

Sorry but I'm not sure what you mean. I'm definitely missing something there

To get an accurate reading post mash you really need to give it a good stir, sugar in the wort is dense and will settle at the bottom of the kettle.

Yeah I didn't do that for sure. So maybe my pre boil reading was high (I believe I did take it from the bottom) but artificially. So then I've not been able to adjust on the fly because I've just assumed it's all good perhaps?

 

[The Baron]

If you have tested your hydrometer and double checked your readings are correct at the correct temperature then it has got to be with the volumes of water you are using which may not be correct if you have not checked and calibrated the AIO systems for being correct.
Check your procedure all the way through and just use one AIO until you get it nearer.
It will be simple thing that you will find it by breaking the procedure down and checking and hopefully something will drop in place

 

[Agentgonzo]

Yeah I didn't do that for sure. So maybe my pre boil reading was high (I believe I did take it from the bottom) but artificially.

This would explain the gravity post mash (first runnings are much higher gravity than the sparged runnings, and it won't mix evenly as it falls into the kettle), but the boil gives it all a good stir, so it doesn't explain the post boil gravity.

 

[Red Raven Brewery]

If you have tested your hydrometer and double checked your readings are correct at the correct temperature then it has got to be with the volumes of water you are using which may not be correct if you have not checked and calibrated the AIO systems for being correct.
Check your procedure all the way through and just use one AIO until you get it nearer.
It will be simple thing that you will find it by breaking the procedure down and checking and hopefully something will drop in place

I've only switched systems because I broke the malt pipe on my old one and wanted to upgrade anyways.

I'm still not 100% on what you mean by the volumes of water. Do you mean how the profile in brewfather will have certain values and they may be off?

I've checked my refractometer and calibrated that with distilled water @ 20° and my hydrometer also seems fine.

This would explain the gravity post mash (first runnings are much higher gravity than the sparged runnings, and it won't mix evenly as it falls into the kettle), but the boil gives it all a good stir, so it doesn't explain the post boil gravity.

I took the reading post mash and sparge I should say but totally get what you mean about the post boil still being a bit weird.

 

[Agentgonzo]

it was +9 on post mast but -10 on post boil.

Can you give us your actual figures from your measured (and predicted) gravity. And also your pre- and post- boil volumes? A 19-point shift just from a boil doesn't make any sense.

Just checking, but did you top up with cold water at any point (I'm assuming not)?

 

[foxy]

I took the reading post mash and sparge I should say but totally get what you mean about the post boil still being a bit weird.

Nothing really weird, you are taking an exaggerated reading post mash, which 'seemingly' throws out your post boil reading

 

[The Baron]

It was regarding the the volume marks on your AIO and how accurate they are as they can be out by a few litres which will make your amount expected to be wrong.
In other words check the measure marks with water so you know wher you are exactly with your volumes

 

[Agentgonzo]

I measured the marks on the grainfather G30 recently, and they were bang on.

https://www.thehomebrewforum.co.uk/threads/help-needed-grainfather-losses.99245/#post-1147610

 

[Red Raven Brewery]

Can you give us your actual figures from your measured (and predicted) gravity. And also your pre- and post- boil volumes? A 19-point shift just from a boil doesn't make any sense.

Just checking, but did you top up with cold water at any point (I'm assuming not)?

Yeah of course.

So expected pre boil gravity of 1.041 but it was 1.050.
Expected post boil/OG of 1.050 but was 1.040
Pre boil volume should have been 29.5l but it was about 28l so I did add the difference and then took the reading.
Post boil should have been 25l but was 28l. That would make sense in losing some gravity points but surely not 10?

 

[Agentgonzo]

So expected pre boil gravity of 1.041 but it was 1.050.

We may be able to attribute this to taking the sample from the unhomogenized wort (ie, stronger wort from the bottom).

Expected post boil/OG of 1.050 but was 1.040
Pre boil volume should have been 29.5l but it was about 28l so I did add the difference and then took the reading.
Post boil should have been 25l but was 28l. That would make sense in losing some gravity points but surely not 10?

Using Dilution And Boiloff Gravity Calculator - Brewer's Friend
Taking your expected values of 1.050 at 25l and using the calculator above would give the same wort a gravity of 1.045 at 28L.

So that explains half the error. Boiling more/stronger will concentrate the wort, upping the gravity.
Have you have comparative brews on these systems before? a 5-point difference can easily be explained by a difference in your brewhouse efficiency from what the recipe predicted.
Can you elaborate on your process and maybe post the recipe and your brewhouse efficiency (predicted in this recipe an also what you have found before on your kit?)

 

[Red Raven Brewery]

We may be able to attribute this to taking the sample from the unhomogenized wort (ie, stronger wort from the bottom).


Using Dilution And Boiloff Gravity Calculator - Brewer's Friend
Taking your expected values of 1.050 at 25l and using the calculator above would give the same wort a gravity of 1.045 at 28L.
View attachment 75438
So that explains half the error. Boiling more/stronger will concentrate the wort, upping the gravity.
Have you have comparative brews on these systems before? a 5-point difference can easily be explained by a difference in your brewhouse efficiency from what the recipe predicted.
Can you elaborate on your process and maybe post the recipe and your brewhouse efficiency (predicted in this recipe an also what you have found before on your kit?)

I just assumed adding 1.5l after the mash was just going to get me to where I needed to be so I'm guessing based on the lower boil off and adding in 1.5l that's where I've sort of gone wrong with volumes.

The Brewfather profile for the brewzilla gen 4 says I should have a brewhouse efficiency of 77% but achieved 70%.
It was my first time using brewzilla so can't compare it to any other brews I'm afraid.

It was regarding the the volume marks on your AIO and how accurate they are as they can be out by a few litres which will make your amount expected to be wrong.
In other words check the measure marks with water so you know wher you are exactly with your volumes

I just assumed that the markings are correct and have tested that actually. Might give it a try later.

 

[The Baron]

Most are not correct some are near some are further away as they are mass produced units.
I know where I am with mine jug filled it carefully , you can also weigh the water which should technically be more accurate

 

[Agentgonzo]

The Brewfather profile for the brewzilla gen 4 says I should have a brewhouse efficiency of 77% but achieved 70%.

Efficiency can also rely on a number of other factors, like grain crush, mash pH, how much or little you sparge.

70% efficiency isn't unreasonable. See what it's like on your next brew and see if it differs.

 

[Red Raven Brewery]

Efficiency can also rely on a number of other factors, like grain crush, mash pH, how much or little you sparge.

70% efficiency isn't unreasonable. See what it's like on your next brew and see if it differs.

Yeah I'll see what happens next time. I do sparge as well and I don't think my method is off but I'll have a think about it all before the next brew day.
Thanks.