Author Topic: Tilt hydrometer bias  (Read 542 times)

Offline David

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Tilt hydrometer bias
« on: April 21, 2021, 12:53:45 AM »
I may be wrong but there seems to be a bit of bias against the Tilt Hydrometer. I have seen on these forums that the first question when using a Tilt is "have you checked the gravity with a 'real' hydrometer". I have another thread that literally the first response was "have you checked the gravity?". Personally, I have used the Tilt almost exclusively for almost two years. My observations are that even "uncalibrated", out-of-the-box the Tilt has ever only been .002 off the "real" hydrometer. (i have four Tilts).
The way I understand it, specific gravity is a "relative" measurement. If you use the same hydrometer for OG as for FG, the difference should be the same. for example, nobody would use one hydrometer for OG and a different one for the FG as the measurement could be off. So why is the first thing everyone asks when the Tilt is used is "have you checked your gravity with a 'real' hydrometer? Is the Tilt not a 'real' hydrometer?
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Offline dmtaylor

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Re: Tilt hydrometer bias
« Reply #1 on: April 21, 2021, 01:12:20 AM »
The Tilt is fussy and does require careful calibration against a "real" hydrometer in many cases.  If your Tilt is reading perfectly, then you are simply lucky.  Many other people including myself have not been so lucky.  While with proper calibration my Tilt reads reasonably accurately for the most part, in cases where a lot of yeast and hop matter become stuck to it at middle or end of the fermentation cycle, the Tilt can read pretty far off actually, by I would say as much as 0.004-0.005 or thereabouts, in my experience.  I am a scientist and I love mathematics and spreadsheets, etc., so I'm not just guessing or imagining.  I KNOW this effect is real.

All this being said... I agree with at least part of what you are saying.  Yes, the Tilt is a "real" hydrometer.  But any real hydrometer was never really intended to read accurately when a lot of gunk is stuck to it.  Only in an ideal environment can it be expected to read very accurately.  And this is true for OG readings.  The OG readings should be accurate within 0.002 if not 0.001 versus a "real" hydrometer.  And this has been my experience.  Only later on in fermentation does it drift a bit. 

Personally I am an advocate of periodically rocking the fermenter in an attempt to knock much or most of the schmutz off the Tilt to get it to read more accurately, and I have seen this help quite a bit.  It doesn't always work, but sometimes does.  So I do rock my fermenter about twice per day during mid and late fermentation.

You don't have to agree with me, but hopefully this sheds a little more light on someone else's experience with the Tilt to help you to understand why people do or say what they do.  I love my Tilt, it's a neat toy.  But I also know it ain't perfect.  It's a tool, and like so many things in this world, tools are about as useful as the people who are using them.

Cheers.
Dave

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Offline Big_Eight

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Re: Tilt hydrometer bias
« Reply #2 on: April 21, 2021, 01:26:03 AM »
I agree with dmtaylor. Some people get Tilts that are more precise as I've seen a few posts about that. Before calibrating my OG is off around 4 points and FG is always two to four points off. My "real" hydrometer reads 1.000 in water at 60 degrees as it should and I apply the necessary correction for the temperature of the liquid.

With that said I love my tilt and its ability to read temp and tell me when gravity has stabilized are game changers for me. A little calibration on my end and it is a fairly accurate tool but I always take OG and FG with a traditional hydrometer.

Offline David

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Re: Tilt hydrometer bias
« Reply #3 on: April 21, 2021, 01:34:21 AM »
The Tilt is fussy and does require careful calibration against a "real" hydrometer in many cases.  If your Tilt is reading perfectly, then you are simply lucky.  Many other people including myself have not been so lucky.  While with proper calibration my Tilt reads reasonably accurately for the most part, in cases where a lot of yeast and hop matter become stuck to it at middle or end of the fermentation cycle, the Tilt can read pretty far off actually, by I would say as much as 0.004-0.005 or thereabouts, in my experience.  I am a scientist and I love mathematics and spreadsheets, etc., so I'm not just guessing or imagining.  I KNOW this effect is real.

All this being said... I agree with at least part of what you are saying.  Yes, the Tilt is a "real" hydrometer.  But any real hydrometer was never really intended to read accurately when a lot of gunk is stuck to it.  Only in an ideal environment can it be expected to read very accurately.  And this is true for OG readings.  The OG readings should be accurate within 0.002 if not 0.001 versus a "real" hydrometer.  And this has been my experience.  Only later on in fermentation does it drift a bit. 

Personally I am an advocate of periodically rocking the fermenter in an attempt to knock much or most of the schmutz off the Tilt to get it to read more accurately, and I have seen this help quite a bit.  It doesn't always work, but sometimes does.  So I do rock my fermenter about twice per day during mid and late fermentation.

You don't have to agree with me, but hopefully this sheds a little more light on someone else's experience with the Tilt to help you to understand why people do or say what they do.  I love my Tilt, it's a neat toy.  But I also know it ain't perfect.  It's a tool, and like so many things in this world, tools are about as useful as the people who are using them.

Cheers.

I have had as you say schmutz collect on the Tilt on occasion, more often than not it has cleared itself when everything settles out. It has been necessary a few times for me to have to carefully fish out the Tilt, clean and re-sanitize to remove the schmutz. For the most part, I have been fortunate not to have experienced as many problems as others seem to have. I do not mean to say that there aren't any problems with the Tilt, just wondering if I missed something somewhere and curious of others experience with the Tilt.
“Whether you think you can, or you think you can't--you're right.” -- Henry Ford

Offline tommymorris

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Tilt hydrometer bias
« Reply #4 on: April 21, 2021, 01:37:05 AM »
I may be wrong but there seems to be a bit of bias against the Tilt Hydrometer. I have seen on these forums that the first question when using a Tilt is "have you checked the gravity with a 'real' hydrometer". I have another thread that literally the first response was "have you checked the gravity?". Personally, I have used the Tilt almost exclusively for almost two years. My observations are that even "uncalibrated", out-of-the-box the Tilt has ever only been .002 off the "real" hydrometer. (i have four Tilts).
The way I understand it, specific gravity is a "relative" measurement. If you use the same hydrometer for OG as for FG, the difference should be the same. for example, nobody would use one hydrometer for OG and a different one for the FG as the measurement could be off. So why is the first thing everyone asks when the Tilt is used is "have you checked your gravity with a 'real' hydrometer? Is the Tilt not a 'real' hydrometer?
Well. Uncalibrated my tilt reads 0.992 in water. It was better before I changed the battery. But, calibrated it is pretty accurate.

Also, I use a different glass hydrometer for OG and FG. I have calibrated those in known gravity solutions.

I love my tilt. I use it on every batch. It is very good at telling the wort temp and showing me the fermentation progress.
« Last Edit: April 21, 2021, 01:39:03 AM by tommymorris »

Offline David

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Re: Tilt hydrometer bias
« Reply #5 on: April 21, 2021, 01:41:22 AM »

Well. Uncalibrated my tilt reads 0.992 in water. It was better before I changed the battery. But, calibrated it is pretty accurate.

Also, I use a different glass hydrometer for OG and FG. I have calibrated those in known gravity solutions.

I love my tilt. I use it on every batch. It is very good at telling the wort temp and showing me the fermentation progress.

Pardon my ignorance, but how exactly can a fixed glass hydrometer be calibrated? Please do not take this wrong, I do not mean any disrespect....
“Whether you think you can, or you think you can't--you're right.” -- Henry Ford

Offline tommymorris

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Tilt hydrometer bias
« Reply #6 on: April 21, 2021, 01:50:02 AM »

Well. Uncalibrated my tilt reads 0.992 in water. It was better before I changed the battery. But, calibrated it is pretty accurate.

Also, I use a different glass hydrometer for OG and FG. I have calibrated those in known gravity solutions.

I love my tilt. I use it on every batch. It is very good at telling the wort temp and showing me the fermentation progress.

Pardon my ignorance, but how exactly can a fixed glass hydrometer be calibrated? Please do not take this wrong, I do not mean any disrespect....
Maybe calibrated is the wrong word. I have measured the instruments bias in a solution of a known gravity. Water and sugar solutions in the FG and OG ranges. I did that when I was worried about high FG measurements. I found my regular hydrometer was off in the FG range. Not sure why. I bought a FG hydrometer. It is much more accurate and much easier to read.
« Last Edit: April 21, 2021, 03:30:54 AM by tommymorris »

Offline BrewBama

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Re: Tilt hydrometer bias
« Reply #7 on: April 21, 2021, 01:54:50 AM »
I love my Tilt. I just don’t trust it for FG. I use it to tell me when a ferment starts, progress, and temp. I use a FG hydrometer for my FG.



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Offline Richard

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Re: Tilt hydrometer bias
« Reply #8 on: April 21, 2021, 02:02:27 AM »
I have made my own leaning cylinder hydrometer that I call Bob because it bobs when I drop it into the fermenter. I abandoned my first attempt, a couple of years ago, because it had problems with the bubbles and dense krausen and I had a difficult time calibrating it over the whole range. When the power switch broke on my circuit board I decided my design was inadequate and I gave up. Then I read that people with Tilts have the same problems with bubbles and krausen and I decided to give it another try last year. I made a larger version with a larger battery and more weight overall to reduce the effects of bubbles and krausen. I had also determined that the gravity is proportional to the tangent of the lean angle to good precision, so a two-point calibration is adequate. I can calibrate in water before the brew and in the initial wort (read with conventional hydrometer) at the start of fermentation. I get pretty good accuracy, within 0.002 or so at the end, but it still goes a bit screwy during active fermentation. The initial bubbles cause it to read too high, then if the krausen is very dense. it may read quite low. Eventually, once the krausen has dropped it reads OK again if it is agitated to shake off any heavy krausen chunks. I could learn almost as much just by looking at the surface, but Bob is more fun. If I brewed in stainless I wouldn't know what was going on.

I like Bob and have no bias against it, but I understand its limitations and shortcomings. I still use a conventional floating hydrometer at the very end as the definitive FG value. Maybe I will eventually come up with a version 3 that is more accurate and reliable, but I'm not there yet and I don't think the Tilt is any better now.
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Offline David

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Re: Tilt hydrometer bias
« Reply #9 on: April 21, 2021, 02:09:08 AM »
I love my Tilt. I just don’t trust it for FG. I use it to tell me when a ferment starts, progress, and temp. I use a FG hydrometer for my FG.



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This kind of touches on one of my original questions. I see specific gravity as, for lack of a better term a "relative" measurement; meaning that if you use the same instrument for OG and FG the relative difference is what matters. If you use one device for OG and a different device for FG, how is that an accurate measurement? Best example I can think of is my bathroom scale NEVER reads the same as my doctors scale, however the DIFFERENCE in both scales are close to the same (A five pound gain or loss is the same on both scales) Using this crude analogy, if I took my weight on my scale for the first measurement, and it was off by say 3 pounds in one direction; then the second measurement on my docs scale which say was off by 3 pounds in the opposite direction, the weight would be off by 6 pounds with no actual difference. How can you get accurate measurements using two separate measuring devices? No matter what it is you are measuring? Again, no disrespect intended...
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Offline BrewBama

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Tilt hydrometer bias
« Reply #10 on: April 21, 2021, 02:25:38 AM »
No disrespect taken.

What’s more important to me is knowing things kicked off within expectation, they’re cruising along ok, and when I’m done so I know to move to my next process.

I actually use four devices for SG: a refractometer during brewday, a hydrometer for OG that I fill when I transfer into the FV, the Tilt in the fermenter, and then a FG hydrometer once it’s done.



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« Last Edit: April 21, 2021, 02:27:16 AM by BrewBama »
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Offline David

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Re: Tilt hydrometer bias
« Reply #11 on: April 21, 2021, 02:50:13 AM »
No disrespect taken.

What’s more important to me is knowing things kicked off within expectation, they’re cruising along ok, and when I’m done so I know to move to my next process.

I actually use four devices for SG: a refractometer during brewday, a hydrometer for OG that I fill when I transfer into the FV, the Tilt in the fermenter, and then a FG hydrometer once it’s done.



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I also use a refractometer on brew day, initially used a hydrometer (Brewing America) for OG, but after several brews with the traditional hydrometer reading +/- .002 of any of my Tilts, have since taken that step out. It it a mistake to rely on the Tilt? given the minimal differences I have seen? How far off have others seen the measurements to be?
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Offline BrewBama

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Tilt hydrometer bias
« Reply #12 on: April 21, 2021, 03:54:57 AM »
I think you should do what you’re comfortable with. However, I routinely see ~5 points difference in FG.

For example: today I packaged a batch that Tilt said was 1.016. My finish hydrometer tells me it’s 1.011. Given the blob on the Tilt as I removed it from the fermenter, I’m more comfortable going with the finish hydrometer.



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Offline waltsmalt

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Re: Tilt hydrometer bias
« Reply #13 on: April 21, 2021, 11:33:19 AM »
I too find that I’m off on my finishing gravity for the same reasons as everyone else: schmutz (or whatever the technical term is) stuck to it.  Going to be a little more diligent with rocking and shaking on the next batch, but it’s going to be a Hefe so who knows how that will work.  Bottom line, still love my tilt for telling me that activity has stopped for 2-3 days.  Just another tool in the tool chest as far as I’m concerned.   

Offline Richard

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Re: Tilt hydrometer bias
« Reply #14 on: April 21, 2021, 03:02:57 PM »
Here are graphs from my Bob hydrometer for two fermentations. The first one was well-behaved.  The reading started to go up when bubbles appeared, then dropped smoothly to final value of 1.008 - 1.009. My conventional hydrometer read 1.011, so just a couple of points different. The second one is crazy. It started off just like the other, but when a layer of very dense krausen formed it began reading ridiculously low. There are several spikes from when I agitated the fermenter to shake off the goo, but it was only temporary. Eventually the krausen dropped and I was able to get the cylinder clear of most gunk and it settled down to a reading of 1.014. My conventional hydrometer gave a final reading of 1.012. That is only a couple of points different in the end, but it was a wild ride getting there!

https://drive.google.com/file/d/1kVs4MzUeUKID_zPni7my4fX50-SK9i4f/view?usp=sharing

https://drive.google.com/file/d/1rEcEWLFHaSG6h24FTK0-zYK1EOXPNRxY/view?usp=sharing
Original Gravity - that would be Newton's