OG Changing?

[Rocker1986]

Hi guys,

I just transferred a batch of pale ale from a cube into my FV, and took a sample for an SG reading. When I took a post boil sample on the brew day, it read 1.046. The sample today is reading 1.043. WTF!

I'm gonna go check the hydrometer in water again in a sec and see if it has gone even further out of whack, because I find this quite ridiculous to be honest, and I'm not sure which reading is the correct one. <_< Is this something that happens a lot?

Edit: Oh and no it had not started fermenting in the cube, the wort smelled perfectly normal as well, as it always does.

 

[manticle]

Hydrometer reading falsely, some variance in temperature between brewday reading and this one or some microorganism has already started the ferment.

 

[Rocker1986]

Yes the temperature was likely slightly different (maybe a degree or two), but I always correct for this when I take the readings. The brew day sample was taken basically from the trub into a large pyrex jug and left on the bench to settle out before tipping 100mL of clear wort into the test jar for the reading. Maybe it is a minor bug that isn't affecting flavour/aroma, as it doesn't happen on every batch.

I will use the brew day reading as the OG then I am guessing?

 

[rude]

I do the same as you

Fill cube from kettle then put a sample into pyrex for a reading when cooled

Sometimes I take preboil readings too

When I pitch cube onto yeast I then take a reading & go by that one

Sometimes the cooled kettle reading is 4 points out always higher

Other times its the same

Beer tastes fine just a temp thing or bad eyes reading the hydro or dregs have a higher reading???

No stress for me

 

[Alex.Tas]

Did you shake the cube before transferring to aerate? I dunno if it is possible, but could there be some stratification within the nochill cube? ie denser wort at the bottom. Its probably pretty unlikely.

Maybe take another SG reading from the wort (that is presumably suitably mixed) in the FV.

As to choosing which value to use, i would chose the higher, as it is better to over estimate alcohol than to underestimate, even when you are only talking around 0.5%abv.
That being said, as you only moved to the FV today, i would give it a good stir, then sample, take reading and use that reading, as it should be representative of what is in the FV.

 

[Rocker1986]

No shaking of the cube. I prefer not to stir up all the shit in the bottom if I can avoid it. I actually have taps on my cubes and stick a short length of plastic tube into them to transfer to the FV (less messy). As per normal I open the tap up and let the bit of crud drain out then take a sample then open it back up again for the rest of the cube to drain into the FV, so if anything it is the bottom wort that the sample is taken from. I doubt that's the problem though. Sugar doesn't settle out like that once mixed unless saturation point is achieved, which is a lot more than is contained in a wort.

I think I will just go with the higher reading, it is more in line with the pre-boil reading I got of 1.038 and after a ~80 minute boil it would have increased by more than fuckin 5 points. Besides, like you say it's better to over estimate the ABV, especially in my line of work. h34r:

The frustration I guess comes from trying to work out the efficiency, these stupid varying SG readings kind of muddy it a bit. Perhaps in future I will just use the post-boil readings as my OG, still take a sample at transfer time for interests sake but ignore it for any other purpose. At least then I'll have some bloody consistency.

The hydrometer is still reading the same 2 points lower that it was on the brew day too, so it hasn't gone any further out of whack.

 

[Nurple]

I had a similar experience with my last brew but it was the other way around (higher by 4-5 points). I let the post-boil wort cool down to room temp before taking a reading to but my higher reading was after tipping the cube into the FV so it was aerated, not straight from the cube.

 

[Rocker1986]

I've had one brew read higher upon putting it in the FV as well. Most of them are the same but sometimes I get one that reads lower for some reason.