Logzor

Recipes 

My other hobby is keeping an reef aquarium, I keep a 150g SPS tank if anyone knows what that means.

I have both a refractometer and a pinpoint salinity meter, which basically measures conductivity. I long ago abandoned my swing arm hydrometer, due to poor accuracy.

I also abandoned my refractometer, due to major errors with the automatic temperature compensation.

So now I use the conductivity meter and measure Ms then convert to SG.

Can I also use this for brewing?

Hermit

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Well, I think salt changes conductivity. Not sure about sugar. Kinda doubt it.

broadbill

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sugars do not conduct electricity, so I doubt you could measure them via conductivity.

What is wrong with a hydrometer?

ajdelange

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Certainly didn't until I Googled them.

Didn't know what that was either until I Googled it. Doesn't look as if such a thing would be very accurate and the ones I found for sale only go up to 1.030 which isn't high enough for brewing as most beers seem to run at least 10 °P (1.040) and most are higher than that (I'd guess 12 °P or 1.052 is average).

You would have to have a refractometer corrected for the changes in RI with temperature for the solution you are measuring in the case of an aquarium the mix of salts you use which I gather is pretty uniform. In the case of brewing the ATC would have to be tuned for wort. Most refractometers that home brewers buy have ATC based on sucrose. This is one of the reasons they often read incorrectly.


As with the refractometer the conversion between conductivity and concentration is dependent on the particular mix of ions expected to be found in the sample. The actual conductivity for a particular ion depends on its mobility, charge and concentration.

In brewing we are interested in measuring "extract". This includes everything dissolved in the wort some of which are ionized and the majority of which (sugar molecules) are not. A conductivity measurement would reflect the ion content of the mash water and be insensitive to the major constituent of wort - sugar.


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