The Puffer Forum

Guys/Gals,

Ok so I have this refractometer that I got on ebay and I found out that it calculates in BRIX, measuring sucrose. I was wondering if I can still use this refractometer?

I found this online BRIX to SG formula...
this is it: SG = 1.000019 + [0.003865613(Brix)+ 0.00001296425(Brix) + 0.00000005701128(Brix)]

Now the problem is, that formula is to convert SG of a sucrose....

My question is, are SG calculated the same way for everything or is it different?

Now I did a test on a 5 gallon of water with 1 cup of salt and it gave me a reading of 1.0062 SG and It looks like it's in the ballpark...... Just want to make sure

I don't think so. Sucrose is a sugar, not a salt, and brix is a measurement of the sucrose in a liquid. http://en.wikipedia.org/wiki/Brix

Sounds like you got the wrong one. Ask the company if you can trade it for a salinity Refractometer.

I would try and return it, but if they won't allow a return/exchange, it should still work. They measure the same thing (refraction of light through water) just with a different measurement scale.

Here is a conversion table:
http://www.fermsoft.com/gravbrix.php

Make sure you calculate the relative error as well using that conversion table (i.e., take the maximum error for Brix measurement (should be in the manual), and multiply it using the table). If the relative error is too high compared to the actual salinities you are measuring, the refractometer is useless.

This is eBay right -- if they won't return/exchange it, tell them you'll leave them negative feedback.

jake_vdb wrote:I would try and return it, but if they won't allow a return/exchange, it should still work. They measure the same thing (refraction of light through water) just with a different measurement scale.

Here is a conversion table:
http://www.fermsoft.com/gravbrix.php

I can't return it because it's from ebay
Yeah I would think it measures the same thing because it just measures the refraction and then with the formula we can determine the weight of the water aka Specific Gravity.....

SG = density of substance(kg/m^3) / density of water(kg/m^3)

Thanks for the conversion table site, but I used the formula and made an excel spreadsheet and I get a more accurate result.

I'll read some more on it....I'll also bring my water to an LFS and have them test it out and see if it's correct.

Thanks for the replies guys

Many things sold from Ebay are from companies. I'd at least try to exchange it. Can't hurt to try.

I don't think I've ever seen a refractometer that didn't have two scales, one for SG and one for Brix. That sucks, but definately ask if you can return it, doesn't hurt to ask!

I use my fish refractometer for beer/mead/wine brewing, its measuring the way the light moves through a liquid and the density, it doesn't matter what is causing the density level, just what the level actually is. So it will work fine, but the conversion is kind of a pain.