hydrometer faulty?

[Gambler]

Hi guys

My hydrometer apears to be under reading...

I started my first beer kit a couple of weeks ago, and had low readings (about 0.008 lower than expected)

I tested it in some tap water today and its reading 0.995 (admititly the water is rather cold)

How close to 1 can I expect tap water to be?

I guess the mis-read will be linier? By that I mean, If it under reads by 0.005 at the start, then it will under read by 0.005 at the end, so in effect, it doesnt really matter as long as I keep using this hydrometer?

Thanks in advance for any thoughts.

 

[PD]

in tap water it should read spot on 1.000
adjust if necessary by either metally adding/subtracting the relevant amount or by gently tapping the hydrometer on a folded towel to move the paper scale back into position

 

[markmark]

in tap water it should read spot on 1.000

That's not quite right pd, but for our purposes it is close enough.
A properly calibrated hydrometer will read 1.000 in pure water. Tap water is far from pure.

 

[kev]

Temperature will have more impact than nasties in your water.

Retest at the appropriate temp. It'll say on the hydrometer.

K

 

[amusedparrot]

admititly the water is rather cold

The temperature of your sample will effect the gravity reading, your hydrometer should tell you what temperature it is calibrated to on it somewhere. Then either get the sample to that temperature or use a site like this one http://www.brewersfriend.com/hydrometer-temp/ to adjust it accordingly.

 

[rpt]

This forum has a calculator for temperature adjusting hydrometer readings. Look at the top left.

 

[Ceejay]

Or there's a very similar calculator on this site. Up there

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[PD]

quote
That's not quite right pd, but for our purposes it is close enough.
A properly calibrated hydrometer will read 1.000 in pure water. Tap water is far from pure.

mine is Yorkshire Water....its pure.... :grin:

 

[Fore]

Mine reads 1.006 in 20 degree water, so I now deduct 6 off every reading.

I guess it's not so much of a big deal, because it's the difference between SG & FG that determines the ABV, and if both are increased or reduced by the same amount, then the difference remains largely unaffected. I guess the danger is ensuring all the sugar has fermented out before bottling.

In any case, I decided the cheap hydrometers are rubbish and have a finishing hydrometer on order (only twice the cost). I'm also putting a refractometer on my Christmas list.

 

[markmark]

quote
That's not quite right pd, but for our purposes it is close enough.
A properly calibrated hydrometer will read 1.000 in pure water. Tap water is far from pure.

mine is Yorkshire Water....its pure.... :grin:

Hahaha
Where abouts are you pd? I'm over near Selby and my water is pretty **** tbh.

 

[Duxuk]

Don't bother with a calculator. My hydrometer is calibrated at 20C. 3C is one point of gravity, so at 29C water would read as .997.