Floating hydrometer reading during boil?

[BostonHomeBrew]

So... stupid idea? I'm going to start a new batch, and want to be better about hitting my OG (last one was low). Would it make sense to take a hydro reading during the boil to so I can adjust by adding water or boiling off to hit the target? I have a floating hydrometer... would that jack it up to boil it?

Thanks again peeps for all the help!!!
BHB

 

[jaycount]

That won't work because you need to take your hydrometer samples at 68 degrees. You can use a correction chart but they're shaky the further you get from 68*F. You can use a refractometer to take gravity readings during the boil but once you have a pre-boil gravity and volume, it's un-needed. Your boil-off will be about the same for every batch...

What kind of brewing are you doing? Extract? All-grain?

 

[Ace_Club]

That won't work because you need to take your hydrometer samples at 68 degrees. You can use a correction chart but they're shaky the further you get from 68*F.

What kind of brewing are you doing? Extract? All-grain?

What he said. Take a sample just prior to the boil and cool it down to 68F or so while the boil is happening. Then take your hydro reading and adjust from there.

 

[BostonHomeBrew]

Ah... I'm doing extract, so it will be pretty close to boiling by the time it's added... So I'm probably out of luck unless I get a refractometer right?

 

[Ace_Club]

Ah... I'm doing extract, so it will be pretty close to boiling by the time it's added... So I'm probably out of luck unless I get a refractometer right?

Why? Even with All-Grain, you're pretty close to boiling when you take the sample.

For you, just pop the sample in the freezer or fill the sink with ice water and cool it off. It's okay if you don't get your reading until 30 minutes into the boil.

 

[dlaramie08]

Take a sample after it's been boiled and cooled down. That's how you do it.

 

[jaycount]

In extract brewing you really don't need preboil or during-boil og's. If you put in the right amount of extract and the right amount of water you will get the right og.

If you're doing a partial boil just top off in the fermenter to the right volume. If you're doing a full boil, figure out the boil off and add your batch volume plus boil off volume.

IMO, you dont need a hydrometer at all pre fermentation for extract brewing.

 

[crazyseany]

if doing all grain... How do you figure out your OG before your boil is complete? Is it something like preboil-final volume (initial hydro reading*PI²)?

 

[nebben]

If doing all grain, even during the boil you can draw off a small sample (drops worth), let the sample cool briefly, and put a drop or two on the lens of the refractometer. Allow another 30 seconds or so for the drips to adjust to the temperature of the refractometer. Take your reading.

If I just completely misunderstood the question, when doing OG, you usually take a gravity reading prior to boiling along with a volume measurement in order to calculate your mash efficiency. If mash efficiency calculations aren't desired, you can skip this step and just measure final volume into the fermenter and OG there (brewhouse efficiency).

 

[RM-MN]

Um...this isn't supposed to be rocket science. You're brewing beer and if you are a little high or a little low, you still make beer.

 

[cullen]

Putting your hydrometer into boiling water stands a very good chance of breaking it.

That said, you can certainly adjust for temperature if you're not exactly at the calibrated temperature.

 

[Yooper]

Putting your hydrometer into boiling water stands a very good chance of breaking it.

That said, you can certainly adjust for temperature if you're not exactly at the calibrated temperature.

Yes, but any sample over about 90 degrees is notoriously inaccurate- to the point of being worthless. It's important to take the sample, cool it to under 100 degrees, then read it and use a temperature conversion chart to convert it to the corrected SG.

You can chill it in a pitcher of ice water (what I do) or stick it in the fridge/freezer.

As was mentioned, do NOT put a hydrometer into a boiling liquid!