accurate?? hydrometer readings - Home Brew Forums
Register Now For Free!

Home Brew Forums > Home Brewing Beer > General Beer Discussion > accurate?? hydrometer readings

Thread Tools
Old 05-21-2007, 07:54 PM   #1
Jan 2007
Posts: 87

I have been trying to get a hydrometer reading of my wort before the boil...err actually during the boil.

So I was wondering if it is even possible to get an accurate reading of boiling wort, or if the mere act of boiling makes it impossible.

Seems like I always get readings of 1.000 or close to it. So I thought, ok, add 42 pts to that and I've got it. Well, that hasn't been too accurate. What do you think?
Up Next: thinking another Hefe
Primary 1: empty
Secondary 1: Fat Tire Clone
Secondary 2: Cider experiment
Kegged: #9, Circus Boy Hefe Clone,
Bottled: CBC Nut Brown Clone, SN Pale Ale Clone, , Two Beagle Dry Stout, Mill Run Stout (first AG), Belgian Tripel
Aging: Hennepin Clone, Blue Ridge Mountain Cider, Maple Syrup Mead
Come and Gone: Nut Brown Ale, Old Man Winter Ale, American Premium Lager, California Ginger Steam Beer, Bavarian Weizenbier

Reply With Quote
Old 05-21-2007, 08:22 PM   #2
Apr 2007
Redlands, California
Posts: 207
Liked 1 Times on 1 Posts

So you're trying to read the hydrometer by dropping it in to a rolling boil? That's a pretty good way to break a hydrometer. You can probably just get away with pulling a sample out, taking the reading, then correcting the reading for temperature (which you would take before and after the hydrometer reading). I think "Designing Great Beers" has a procedure for this, you might check there.

Reply With Quote
Old 05-21-2007, 08:24 PM   #3
For the love of beer!
Orfy's Avatar
Sep 2005
Cheshire, England
Posts: 11,732
Liked 98 Times on 62 Posts

Well if that's the case then regardless of the brew then it'll always be 42.

Simple answer is no you can't and why would you need to.

If you are looking to hit a gravity then you need to know the gravity going in and how much you've boiled off then you can calculate it.

Or take a sample, chill it and do a temp adjustment if you don't want to wait for it to chill to 60F.
Have a beer on me.

Reply With Quote
Old 05-22-2007, 02:43 PM   #4
gonzoflick's Avatar
May 2006
Orlando, FL
Posts: 466
Liked 2 Times on 2 Posts

Unless you are doing full boils then you need to add water afterwards anyways so that would give you a completely different reading.
Primary: Fullers ESB Clone
Secondary: Hierra Sevada Pale Ale
Bottled: NOTHING

Reply With Quote
Old 05-22-2007, 03:46 PM   #5
zoebisch01's Avatar
Nov 2006
Central PA
Posts: 5,182
Liked 10 Times on 10 Posts

I am convinced that I don't trust the correction equations above like 110 F or so. Just a gut instinct...I could be wrong, but since I have never seen how they derived the equations I am skeptical. There is something about it that bothers me....but it could just be me .

Best way imo (as has been mentioned), is just draw a sample out at the end of the boil and when it cools read it
Event Horizon ~ A tribute to the miracle of fermentation.

Brew what you like. Do this, and you will find your inner brewer.

Reply With Quote
Old 05-22-2007, 04:04 PM   #6
david_42's Avatar
Oct 2005
Oak Grove, Oregon, USA
Posts: 25,599
Liked 158 Times on 148 Posts

Between the steam bubbles and the fluid motion, it would be impossible to get a valid reading.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"

"I would like to die on Mars, just not on impact." Elon Musk

Reply With Quote
Old 05-24-2007, 09:25 PM   #7
Dec 2005
San Diego
Posts: 848
Liked 6 Times on 6 Posts

Refractometers work well for that. Just drip one drop off your stirrer ontot he refracomter. The mass of the tool cools the drop instantly, wa-laaa, your sugar content.
So far, I've had more experience thinking than I've had don't think they are mutually exclusive, do you?

72 batches so far,
48 wine, mostly Loquat, peach, plum, prickly pear
23 beers and ciders
1 sauerkraut
1 Tequila, from a prickly pear wine experiment that didn't work. I call it "Prickly Heat"

Reply With Quote
Old 05-25-2007, 01:04 PM   #8
Sep 2005
Nantwich, Cheshire, England
Posts: 20

Never have used a hydromthingy, why make it complicated. It's a wonder the boil water didn't crack it !

Reply With Quote
Old 05-25-2007, 04:55 PM   #9
Got Trub?
Apr 2007
Washington State
Posts: 1,538
Liked 10 Times on 8 Posts

I would recommend you take a reading before the boil.

You need to cool the wort as the hydrometer is calibrated to read (usually) at 60F. As mentioned above the further your temp is from that the less accurate your correction will be. I use:

Then knowing your preboil gravity and knowing how much evaporation your boil produces you can determine if you need to add volume and how long you need to boil for to hit your target gravity.

Reply With Quote
Thread Tools

Similar Threads
Thread Thread Starter Forum Replies Last Post
How do I get accurate hydrometer readings? chrispykid Extract Brewing 2 02-18-2009 11:00 PM
Getting an Accurate Hydrometer/Refractor Reading After the Boil RLinNH General Techniques 3 06-11-2008 12:51 AM
accurate hydrometer read w/split pot boil? tranceamerica General Techniques 6 05-27-2008 04:39 PM
how do i test my hydrometer to make sure it is accurate? funkydrummer88 Beginners Beer Brewing Forum 4 04-11-2008 05:46 AM
getting accurate gravity readings during sparge boothbrew All Grain & Partial Mash Brewing 10 03-18-2008 05:00 PM

Forum Jump