How and when should I take a gravity reading during my fermentation?

[Finlandbrews]

I would like to take a gravity reading of my fermented wort but I'm worried about oxygen pick up? After how many days into fermentation would you advise taking a reading? What technique do you use to avoid oxygen pick up? Is it better to take the reading when wort is at fermentation temperature or when cold chilling? Or should I take the reading only when I start bottling?

 

[ncbrewer]

There are different opinions about sampling. I don't sample until two days before bottling again on bottling day, and again on bottling day to be sure gravity is stable. Oxygen and contamination are the concerns. Others sample often - hopefully some of them will post here. I ferment in a bucket and use a measuring cup to carefully dip out a sample. I think most use a wine thief if the beer is in a carboy. I don't think the beer temperature matters for taking a sample. Sampling is one of the many "personal preference" items in brewing.

 

[MeanLowerLow]

I use a thief for all samples (bucket or carboy) and recommend you get one. I spray it liberally with star San, then open the fermenter and take the sample as quick as possible to minimize exposure.

I like to wait about three weeks before kegging. I usually take a reading a day or two before kegging and again before I keg just to confirm I've reached my FG.

 

[Queequeg]

I have a tap in the fermenter and resupply the head space with CO2.

 

[JONNYROTTEN]

A cheap turkey baster sprayed with starsan.At room temp(your hydrometer should say what temp in small letters inside the probe).At least 7 days in will most likely insure complete fermentation and you'll have alcohol will lessens the chance of infection.These days I usually just wait till I transfer to keg to take a reading.

 

[mattdee1]

I just wait 10-15 days based on my available time and pull a sample. And really, that sample is just to see what my FG is, not to verify that it has been reached. I then bottle as soon after that as life allows, and don't even bother with any more samples.

Granted, I tend to brew "easy" beers (1.050ish OG) that are very predictable. Higher gravity stuff would probably merit a bit more scrutiny on FG stability.

 

[Finlandbrews]

Thanks for all the feedbacks. Can a spigot on the fermenter be better to take a sample than using a wine thief? Will there be less oxygen pick up?

 

[ncbrewer]

Some brewers use a fementer with a spigot. Apparently it's better for preventing contamination. Air still has to come in thru the airlock, but at least it's just the exact amount needed to replace the volume lost. But if you use a swamp cooler, the spigot has been sitting in unsanitized water for a while. I don't think I could live with that. You might get some of the airlock liquid sucked back into the fermenter, too. That might be ok if it's Star San solution?

 

[Casedeville]

Can a spigot on the fermenter be better to take a sample than using a wine thief? Will there be less oxygen pick up?

I think a spigot would be the best way to pull a sample if you have it. It's near impossible to prevent ANY oxygen pickup while homebrewing unless you have a closed system with CO2 pushing the beer around. The goal is minimizing it as much as possible.

When I first started homebrewing, I would sample all the time, but I was wasting so much beer that way and it doesn't help speed up the process at all. Now I just wait about 2 weeks for fermentation to finish and take a reading when I'm racking to the keg so that I can calculate my ABV. I'm sure it's done fermenting sooner, but I'd rather be sure and not waste more beer.

 

[ChelisHubby]

When you are starting out the first sample should be after 2 weeks. After you have done a dozen brews you will have a good Idea of when the yeast has finished. Now if you are doing High gravity brews say 10.70 or more than they break all the rules and can take 3 weeks or more. So take your first sample at 12 days and see if the second sample on day 14 is the same, if it is the same bottle or Keg.