Hydrometer error/glitch in the matrix

[simon12]

After using a new finishing hydrometer for the 1st time I decided to check it in tap water and it read 0.998 so I checked with another hydrometer and same reading and again with a 3rd same. So changed the water same again with all 3 so I took a picture to confirm it. After taking the picture I looked at it closely and it was reading 1.000 so I checked all 3 hydrometers again and they all started reading 1.000. Don't really have a point in posting this but i'm putting it down to a glitch in the matrix.

 

[britton]

Water temperature?

 

[simon12]

Didn't think of that maybe the world does still stick to scientific laws would tap water temp to room temp make that difference?

 

[LeeH]

If it’s not 20 degC you have to use a fudge factor.

 

[Bigcol49]

Hi!
Yes, cooler water would give a lower reading. Perhaps the faffing about with the three hydrometers was enough to bring the water temperature closer to 20°C.

 

[simon12]

Just to confirm I have replicated this water at the temp it comes out the tap reads 0.998 and after half an hour gets to 1.000 sorry to waste all your time, I totally forgot temperature made a difference and don't have a suitable thermometer at the moment to check.

 

[-Bezza-]

Don't be so hasty. Being able to repeat might suggest a full-on bug in the Matrix rather than just a glitch.

 

[terrym]

@simon12
Warmer water (than the calibration temperature) gives a lower SG reading i.e. density decreases. For clean water with a measured SG of 0.998 (and assuming your hydrometer is calibrated at 20*C and reads correctly). the temperature would be in the range 28-31*C. This is unlikely for mains water straight out the tap, but if you drew off some hot water before you took your sample, this is entirely probable. Cooling to room temperature will mean the temperature is at or near 20*C, the sample density increases and the measured SG will rise to 1.000 (again on the assumption that the hydrometer reads accurately).

 

[simon12]

I just found a thermometer so will investigate again tomorrow. Is there a department to report glitches in the matrix if thats what it turns out to be?

 

[-Bezza-]

I just found a thermometer so will investigate again tomorrow. Is there a department to report glitches in the matrix if thats what it turns out to be?

Yes, but it's a convoluted process involving a Nokia 8110 and some dodgy pills.

 

[chthon]

Don't be so hasty. Being able to repeat might suggest a full-on bug in the Matrix rather than just a glitch.

Then it's not a bug, it's a feature...

 

[arcain]

Maybe it's something to do with air/chlorine in the water as it comes straight out of the tap and then this gas dissipates after 30 mins.

 

[simon12]

Ok water from tap is showing 14C and hydrometer is reading between 0.998 will leave in an hour and check again.

 

[simon12]

Temp now 19C SG gone up a tiny but definite amount.

 

[simon12]

Now 20C and 0.999

 

[simon12]

Now 21C and still 0.999

 

[simon12]

Now still 21C but back to 0.998 so no idea what's going on

 

[Drunkula]

Make sure the hydrometers are all really clean, then spin them when you put them in.

 

[cushyno]

Maybe it's something to do with air/chlorine in the water as it comes straight out of the tap and then this gas dissipates after 30 mins.

This is a definite possibility.

Anything that remains in suspension in a liquid such as yeast or trub can affect the SG because it's effectively changing the density of the liquid. The effect may be slight or noticeable depending on how much is in suspension. Gas has a similar effect, whether it is CO2, oxygen, or whatever because it affects density. Also, bubbles that cling to the hydrometer can cause it to float better.

Therefore gas absorbed in water can make it less dense and cause the hydrometer to sink lower, whereas gas escaping from the water can cling to the hydrometer and cause it to float more.

Your hydrometer is likely only accurate at 20°C in non-fizzy beer that has most yeast and trub dropped out of suspension.

Taking readings of wort prior to fermentation must be done cooled to 20°C, but even then will be affected by particles of grain in the wort. You are rarely going to get a precise reading, but if you accept the margin of error and remove as many variables as you can then a hydrometer is probably good enough for home brew purposes.

Repeated dipping or spinning the hydrometer in your liquid helps remove bubbles and can make a difference of about 2 points on your SG reading, I have found.

 

[simon12]

I left it there until 22:30 spun it bobbed it and it remained at or between 0.998 and 0.999 its a finishing hydrometer so its impossible to be reading it wrong and it never got to 1 like it did last time. I was hoping to learn something from this, now would be happy to work out whats going wrong.