Bitx And Plato

[pint of lager]

To understand the readings of feremnting wort, you must get a grasp of real and apparent attenuation.

Real attenuation is the actual amount of malt sugars remaining, as shown by the refractomter.

Apparent attenuation is the amount shown by the hydrometer, which is actually an incorrect reading.

Before pitching the yeast, the wort is a mixture of malt sugars and water. After fermentation starts, there is less sugars and more alcohol. Alcohol is less dense than water, and the hydrometer is a poor tool for measuring two fluids with different densities, and sugar. The less dense alcohol causes the hydrometer to float lower in the fermenting wort.

If you took a 200ml sample of fermenting wort, remove the alcohol by boiling, then add water to bring the volume back to 200ml, then floated your hydrometer in this sample, the hydrometer would show a much larger reading, and give the real attenuation.

So make sure you use your favourite brewing software to track the refractometer reading of the ferementing wort and give you apparent antenuation like you are used to with the hydrometer.

For the first few brews, I suggest you do a hydrometer reading and refractometer reading at the same time, to give you a good understanding of what is happening.

Using a refractometer really makes you pay attention to the residual sweetness that must be balanced by the correct amount of hops.

 

[Batz]

so should you sparge till you have 1.0 bitz or SG of near 1.000

 

[Doc]

Batz,

I stop my sparge when I hit my target volume usually at 5-7 brix.
If my wort collection is really low I let it go to 3 brix (only had to twice).

Beers,
Doc

 

[breaky]

pint of lager said

So make sure you use your favourite brewing software to track the refractometer reading of the ferementing wort and give you apparent antenuation like you are used to with the hydrometer.

Yep, did that

For the first few brews, I suggest you do a hydrometer reading and refractometer reading at the same time, to give you a good understanding of what is happening.

Yes, did that too. As I said in my previous post -
"i entered the brix and the OG into the fields of the 'gravity during
fermentation' box in promash and got a gravity reading of ....1.00405 instead of the real reading of 1.010"

Provided you enter the correct info (which I did) Promash does it for you doesnt it???
Breaky

 

[user 384]

If you now the beers OG you can take a brix reading and get the final gravity, but you'll just need software to do some calculations which are almost impossible for he human brain.

For those who want to have a shot at doing the calculations themself here is the equation.

OG = (100*((194.5935 + (129.8*SG) + ((1.33302 + (0.001427193*R) + (0.000005791157*R^2))*((410.8815*(1.33302 + (0.001427193*R) +
(0.000005791157*R^2))) - 790.8732))) + (2.0665*(1017.5596 - (277.4*SG) +
((1.33302 + (0.001427193*R) + (0.000005791157*R^2))*((937.8135*(1.33302 +
(0.001427193*R) + (0.000005791157*R^2))) - 1805.1228)))))) / (100 +
(1.0665*(1017.5596 - (277.4*SG) + ((1.33302 + (0.001427193*R) +
(0.000005791157*R^2))*((937.8135*(1.33302 + (0.001427193*R) +
(0.000005791157*R^2))) - 1805.1228)))))

OG is in degrees Plato, SG is the hydrometer reading in specific gravity and R is the refractometer reading in Brix.

This equation will solve for for the estimated OG when the refractometer and hydrometer readings of a beer are known. You can then manipulate it to solve for SG, if you know the OG and R of a beer.

Look's very complicated but a simple program like Excel makes it much easier (if you can be bothered entering the formula). OR just use Promash, BeerSmith etc.

Cheers
MAH

 

[Hoops]

Tried it in Excel but still can't upload those file types.
Will compare it to Promash and see whether I did it right or not.

 

[user 384]

Hoops

I've been following this On HBD and today Bill Pierce posted the equation again after there was a mistake in the formula. Here is the correct formula:

OG = (100*((194.5935 + (129.8*SG) + ((1.33302 + (0.001427193*R) + (0.000005791157*(R^2)))*((410.8815*(1.33302 + (0.001427193*R) + (0.000005791157*(R^2)))) - 790.8732))) + (2.0665*(1017.5596 - (277.4*SG) + ((1.33302 + (0.001427193*R) + (0.000005791157*(R^2)))*((937.8135*(1.33302 + (0.001427193*R) + (0.000005791157*(R^2)))) - 1805.1228)))))) / (100 + (1.0665*(1017.5596 - (277.4*SG) + ((1.33302 + (0.001427193*R) + (0.000005791157*(R^2)))*((937.8135*(1.33302 + (0.001427193*R) + (0.000005791157*(R^2)))) - 1805.1228)))))

Cheers
MAH

 

[dreamboat]

can't be bothered with all that myself...
looks like a good job for promash


dreamboat