Tilt Gravity data discussion

[Pete Finch]

Hi everyone, so my first post here and because I had my first experience with a Tilt this week and would love some community feedback
So I brew in corny kegs, under pressure, purging the serving kegs with CO2 from fermentation. I tend to leave the pressure low for the first day, then ramp it up slowly to 25psi over the next 24 hrs, then maintain until FG is achieved.
My yeast was Nottingham, 1x packet and I had 17L wort in each 3x kegs.
My grain bill was 10Kg Ale Malt, 500g Amber and 1.5Kg Medium Crystal, not that this matters; I'm just using up some old grain I have lying around.. and 2Kg honey because I also keep bees and I like honey.
I mash in and boil with a Brewzilla 65, but I don't chill, I just put the hot wort straight into the kegs, with 66g Motueka hops at around 90C. Once cooled, normally overnight, I'll add the yeast, and the tilt, and away we go. I have 100g Talus hops waiting transfer in the serving keg. I also have 10ml of Pacific Jade hop extract oil in the boil, but I'm going to stop doing this now I'm fermenting with the hot side hops.
So far so good. Bit of a different process to normal brewing, but it makes good beer and I don't waste all that water/time on chilling the wort. Added bonus my kegs gets extra pasturised (they are of course cleaned and sterile anyway)
So thats my process but here is the tilt data that makes no sense to me
I have a heating belt that heats below 22C but we never go there, the blue line is the SG.
See how the gravity drops to the lowest of 0.992 before creeping back to FG at 1.011
If the tilt had any krausen/yeast attached to it, it would sink, thereby increasing the gravity reading; if the tilt had bubbles on it, it would elevate it lowering the gravity reading.
In my opinion the tilt should not have any bubbles towards the end of fermentation..
So I'm wondering what happened here, and would appreciate any feedback from you all on this bizarre data.
This is my first tilt usage, so I have no other brew data to compare it to. If any of you have some, please post your data too.
Additional; some of you may be wondering why there is no OG time line before it starts fermenting; this is because I got the tilt 12hrs after pitching, so I cleaned it, and dropped it in at the beginning of the ferment, hence the ferment has already started at the beginning of the data.
Thanks everyone; I'm in New Zealand so please bear with the timezones for my responses..
Cheers all
Pete

 

[Minbari]

I have noticed this on my tilts as well. My guess is that there is still some dissolved co2 coming out of suspension, even if you don't see much air-lock activity. As it comes out, becomes more dense. Also, the temp does play some effect on the SG calc they use.

In the end, I don't depend on this thing for super accurate readings. It let's me know what the trend is in the fermenter and when it's done.

 

[Donoroto]

Welcome to Brewer's Friend! I also use a Tilt.

I see this kind of reading as well, but not as deep a dip.

I've said this several times: the Tilt reads well in sugar water, but beer with krausen and CO2 affect the readings significantly.

Considering that, use the tilt for a relative reading and mostly ignore the absolute readings. For example, on 3/26 at 0:00 your fermentation was done. The FG might be 1.012 or it might not, but what you definitely know is that it is not changing.

Of course 'done' here means SG is stable. Many will allow more time for fermentation to really finish, as the yeast is still working on things that don't affect SG. But you know that.

You will see a coating of krausen sludge on the Tilt when you take it from the keg, that affects the reading for sure.

 

[Sunfire96]

This is what my typical tilt reading looks like

A few small dips, but mostly consistent in it's trend.

25 psi seems high for an ale yeast?

 

[Craigerrr]

Welcome to Brewers Friend!
I don't use a tilt, but many do, I am sure you will get plenty of support on that here!

 

[Over The Cliff Brewing]

I use the tilt mainly for temperature and to see relatively where the fermentation is on the days in the fermenter. Since I'm a homebrewer, the absolute ABV is not highly critical as it is with a commercial brewer.

 

[Pete Finch]

Thanks everyone, appreciate your feedback
yeah, I agree the data I'm actually after is the relative reading, knowing when its stopped and approximate FG. Its nice to see how it's tracking over the day. I'm not watching it honest(!)
Dissolved CO2 coming out could be part of it, raising the tilt, but it should not be degassing, and the pressure was stable (if a little high!)
Sunfire you say 25psi is a bit high, and I tend to agree with you after searching the web for ale fermentation pressures. brewing under pressure is relatively new to me; the spunding valves I have go up to 25psi, so I figured thats ok, and the beer is fine; I've not noticed any off flavours. worth a test though; I have three kegs, so I can leave one alone, one at 15 and one at 25 and compare.
Actually knowing when the beer is finished is key data for me; I used to leave it for 2x weeks, but now I leave it for 24-48 hrs after hitting FG before cold crashing it, so grain to glass time is improved. my next step is transfer on to the dry hops already in the serving keg, warm up the kegs for 3x days for dry hopping and then chill again to serve.
anyway, back to the Tilt, this one was actually my friends, but I have my own now, so the next brew may be different. Temperature wise the ambient is around 25C here at the moment, so no heating, but I don't have cooling tech available at the moment other than kegerator, and there is always some beer/mead/cider in there.. besides Nottingham is a beast of a yeast; I had to brew at 33C a few years ago and the beer was also fine..
I tried the Brewbrain Float for a while, since it's proper wifi enabled, but I had very little success with it; just poor comms and poor data; in my mind the tilt is the superior product.
Anyway, again, thanks for your input and I'll post my different tilt data next time I brew for a comparison.
By the way, those of you that have the pi, you should also run pihole on it and kill the ad's on your network.. mine is a 2b (old) and it runs both services fine without issue.
cheers!
Pete

 

[Minbari]

All my web enabled devices are on Thier own network on a dedicated branch of the firewall. Can't get to the other parts of my network from the brewery

 

[Donoroto]

I used to leave it for 2x weeks, but now I leave it for 24-48 hrs after hitting FG before cold crashing it, so grain to glass time is improved.

I wonder if that is too short a time. After SG is stable, the yeast is still doing (important) things to the beer. I suggest holding the beer for a time equal to the active fermentation - meaning, if it took 4 days to come to stable SG, then let it continue another 4 days or so.

 

[Sunfire96]

I wonder if that is too short a time. After SG is stable, the yeast is still doing (important) things to the beer. I suggest holding the beer for a time equal to the active fermentation - meaning, if it took 4 days to come to stable SG, then let it continue another 4 days or so.

Those things can still occur during cold crashing and conditioning. Time after FG is more important than temperature

Also @Pete Finch have you thought about dry hopping at cold temperatures? Lots of fun new science out there these days. Plus it saves you the time it takes to warm up and then rechill your beer. Once my fermented beer is cold I try to keep it cold because warm temp fluctuations can decrease the shelf life of the product

 

[Pete Finch]

Hey all, just transferring tonight, fermentation took four days and I left it four days before cold crashing.
I have tried dry hopping chilled, but I found the hoppyness very muted. After warming up to 25C for a few days then chilling to serve I got a significantly better brew.
The reason I brew like this is to keep O2 out for the longevity of the hops. I suspect I'm allowing O2 on to the hops as they sit in the serving keg, but not for long, maybe 24hrs or so until the CO2 starts transferring from the fermenting kegs, but you can smell them as the air is pushed out. i'm not sure how else to do it? perhaps allow the CO2 to push the air out, then after a day or so, open the the serving keg and add the dry hops; the bottom of the keg will now be full of CO2.. and the remaining CO2 can flush out any air that got into the keg during the transfer. yeah, I might do that next time, add the hops a day or so after pitching and ferment is in full flow.
I think my hop utilisation is about 10g/L, wet and dry hop.
cheers all!

 

[Donoroto]

I found the hoppyness very muted.

That could make one unhoppy...

As far as oxygen in the hops, don't worry. Hops and oxygen are not mortal enemies like beer and oxygen. You cannot help but smell the hops, and although I guess weeks in air will let the volatile oils evaporate, in the timeframe we're talking about you would be hard-pressed to even measure the amount of oils lost.

 

[Pete Finch]

but then why does the hoppiness of beer degrade quickly with O2 ? before when I used buckets to ferment, the hops would be gone in a few weeks; now, in kegs, with no O2, they remain until the beer is gone.. so I'm very hoppy

 

[Craigerrr]

That could make one unhoppy...

Don... your Bad Dad jokes are the worst my friend!!!

 

[ttsalo]

I have had the Tilt show quite wrong SG values when dry hopping or when there is a thick layer of yeast stuck on top of it... Just did a saison where it was showing a really nice curve down to 0.999 but when I kegged the beer, it was actually 1.009, and there was quite a cake of yeast stuck on the Tilt. This doesn't really matter as I'm not looking for a specific FG, just the rate of change. Even if Tilt was 100% accurate, my processes are not and I don't know what the real expected FG of any specific beer is going to be until I see where it stops...

When adding loose pellet hops I have seen even weirder curves, both the "noise" showing heavy activity but the average not dropping, and the SG value dipping to unrealistic levels right after adding the hops.