Harry Bloomfield
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I have a couple of hydrometers, but I'm wondering if taking SG values might be much easier with a cheap refractometer? What are pros and cons?
Refractometers
- Thread starter Harry Bloomfield
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I only use the refracto on brew day. Pros are you only need a drop of wort and dont have to wait for it to cool. Im not convinced its quite as accurate as the hydro but is good enough to estimate SG so that I can dilute to hit target.
Yeah I find a refractometer useful as you can check gravity at more different points during brew day, helps get a feel for your process and how e.g mash, sparge, boil and any dilution impact the final OG.
I also find them useful for starters where I don't really want to waste wort in the sample tube, but it's nice to make sure you are in the right ballpark with gravity, e.g didn't boil off too much etc.
The main con is it doesn't work after fermentation starts due to the alcohol, so you really need a hydrometer as well (unless you use a correction calculation, which I've not yet tried).
I also find them useful for starters where I don't really want to waste wort in the sample tube, but it's nice to make sure you are in the right ballpark with gravity, e.g didn't boil off too much etc.
The main con is it doesn't work after fermentation starts due to the alcohol, so you really need a hydrometer as well (unless you use a correction calculation, which I've not yet tried).
Harry Bloomfield
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The need for correction, is the part which is really confusing me. I thought measuring the sugar's conversion to alcohol, was the whole point of checking SG?
Something else is also causing me confusion and I keep seeing mention of it - why is the sample used for the hydrometer wasted? If I have sterilised both the sample tube and the hydrometer, why can't the sample just be returned back into to the FV?
Something else is also causing me confusion and I keep seeing mention of it - why is the sample used for the hydrometer wasted? If I have sterilised both the sample tube and the hydrometer, why can't the sample just be returned back into to the FV?
I do just that without any issues.
scomet
Member
Use a refractometer and one of these graphs or do the math
Good idea, but can you post a link? It's too blurred to be useful.
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scomet
Member
Sorry about the crapy image I can't post it in any higher resolution!
You'll have to go here and go the thread #3 and open image in new window then save as a jpeg, it was made by a forum member on AHB 1o years ago
https://aussiehomebrewer.com/threads/refractometer-sg-alcohol-correction-chart.47454/
Good luck
You'll have to go here and go the thread #3 and open image in new window then save as a jpeg, it was made by a forum member on AHB 1o years ago
https://aussiehomebrewer.com/threads/refractometer-sg-alcohol-correction-chart.47454/
Good luck
Zephyr259
Landlord.
I use a digital refractometer for everything now. Spent the first year of using it comparing it to a hyrdometer to see what it's correction factor was. I use the brewer's friend conversion here, although I've formed it into my own spreadsheet using the formulae it runs off.
Funny thing is that it doesn't work in mead which was the primary reason for getting it, can't be wasting sample jars every time when you only have 5L and need to track fermentation closely for nutrient additions. Works fine for OG but as soon as it starts fermenting the refractometer reading drops like a stone then doesn't really move so looks like the batch has stalled. I'm also wondering if it's no good for measuring FG in sours as it says both my batches are still over 1.010 after almost a year conditioning.
I went digital as I read that regular ones can give different reading on the same sample which would be just enough to make it pointless in confirming FG.
@kelper The issue with sugar and alcohol both affecting FG isn't as relevant on hydrometers as reducing sugar and increasing alcohol both reduce gravity, where with refractometers the alcohol raises the reading substantially. The 131.25 factor takes into account the fact we use apparent attenuation rather than real attenuation, I calculate both in my spreadsheet and they work out much and such the same.
Funny thing is that it doesn't work in mead which was the primary reason for getting it, can't be wasting sample jars every time when you only have 5L and need to track fermentation closely for nutrient additions. Works fine for OG but as soon as it starts fermenting the refractometer reading drops like a stone then doesn't really move so looks like the batch has stalled. I'm also wondering if it's no good for measuring FG in sours as it says both my batches are still over 1.010 after almost a year conditioning.
I went digital as I read that regular ones can give different reading on the same sample which would be just enough to make it pointless in confirming FG.
@kelper The issue with sugar and alcohol both affecting FG isn't as relevant on hydrometers as reducing sugar and increasing alcohol both reduce gravity, where with refractometers the alcohol raises the reading substantially. The 131.25 factor takes into account the fact we use apparent attenuation rather than real attenuation, I calculate both in my spreadsheet and they work out much and such the same.
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@Zephyr259 have you looked for a digital hydrometer? Could you weigh a few cc's with a jeweller's scale? I mean use a syringe to draw off 5 millilitres and weigh it accurately? I just sterilise my hydrometer and trial jar and pour the sample back. (after a wee taste).
Zephyr259
Landlord.
I've been using a digital hydrometer for the past 2 years. :-) In theory you're idea would work fine, weigh the syringe before and after filling then scale up. But then any errors would be multiplied up and it's probably better to just use a hydrometer.
Drunkula
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Adding to what Zephyr said about readings, refractometer readings aren't linear as soon as alcohol enters the equation so for instance a 5 brix drop with a starting gravity of 1.039 would mean you had 4.07% alcohol, with a 1.061 starting gravity the same drop would give you 4.54%. I absolutely love refractometers. Hydrometers get on my wick.
Harry Bloomfield
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Interesting idea, I have a jeweller's digital scale I bought originally to look at mixing my own vape liquids by weight.
Thinking about it, the difficulty is in measuring the volume accurately, which was why I decided that measuring weight was a much more accurate way to make vape liquids and bought some precision scales.
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BassoonBrew
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I use a digital refractometer now too. There are some handy online tools for converting the readings both before and after fermentation here:
https://www.brewersfriend.com/refractometer-calculator/
I've double-checked a few times with a "normal" hydrometer, and they seem to work well. I'm not looking for mega-accuracy, but the small quantity of wort and speed of reading make life much easier.
https://www.brewersfriend.com/refractometer-calculator/
I've double-checked a few times with a "normal" hydrometer, and they seem to work well. I'm not looking for mega-accuracy, but the small quantity of wort and speed of reading make life much easier.
Harry Bloomfield
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The refractometer I have ordered is marked in SG and supposedly temperature compensated (?). Will it still need any conversion calcs?
Drunkula
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