Bought a new hydrometer and it isn't accurate

[zacster]

My wife knocked over my flask and hydrometer, and they both broke. So I ran out to my LHBS and bought new ones. Well, the shop didn't have any stock on either so they broke into one of their kits to get them. They weren't the same as what I had but I figured it would be fine.

Tonight I decided I wanted to use them so I retrieved them from the car where I left them. I put tap water into the flask and stuck the hydrometer in and it read 1.005. WTF? I could accept if it is off by .001 but .005? And then I realize the flask is much bigger than what I have, so to use it I'll be wasting more beer to take a measurement. They weren't expensive, but still I'd expect a little more accuracy. I'm sure I saved a newbie from getting frustrated that his brews aren't measuring the way the recipe says.

I think I'll shop around for an accurate one.

 

[acidrain]

Were you at the correct temperature?

 

[tally350z]

use either distilled or RO water also..

 

[Blitzkrieg]

And worse case scenario, take 5 points off your future readings.

 

[orangehero]

It may not be accurate but it's probably precise, which is all you really need. Sometimes the paper scale will shift, but all the readings should just be shifted by the same quantity.

 

[Indian_villager]

Accuracy is one thing. Repeatability is another, if it is consistently off by the same value you are set. Also as mentioned earlier, distilled water and temperature correction. Seeing as you are from Brooklyn I am going to assume your cold tap is still pretty cold.

 

[petrolSpice]

Use distilled water at the correct temp. When I tested mine with tap water at whatever temp is came out at, it was 0.003 off. With distilled water at 60F it was spot on.

 

[agrazela]

Your wife broke your stuff. Mm Hm.

 

[zacster]

Your wife broke your stuff. Mm Hm.

Except she really likes my beer...

 

[zacster]

And I hear what you're all saying, but at the same time I'd never accept a device that was off that much if I can't permanently adjust it. Would you accept a ruler that was off a half an inch?

Also the flask takes at least twice as much liquid to get a measurement.

 

[LordUlrich]

The paper inside tend to slide around, either (easy way) do the math, or (riskier way) flip it over and gently tap it on soft surface to get the paper back where it should be. Before you do either confirm that it is indeed off as much as your first measurement indicated. Cold water or high mineral content could throw it off quite a bit.

Hydrometers are a really simple tool, there is really no way for it to be inaccurate just poorly calibrated. Expensive hydrometers have better scales, stand up to abuse better an allow more precise measurements but neither will drift.

 

[zacster]

I bought a different one that is spot on. I'll keep the other as a spare and just remember to subtract .005 each time.

 

[SpeedYellow]

I've owned several and they're not typically spot on. No big deal; just add or subtract whatever is needed based on calibrating in distilled water. One of these days I also need to calibrate in a sugar solution too, to make sure it's reading higher-gravity stuff properly too.