I left a little of the fermenting wort in an empty bottle with a loose towel plugging it, so I can take readings without opening my bucket (I will take my final reading with the full batch though).
Actually that "satellite fermenter" idea will only tell you WHAT YOUR BEER WILL FINISH AT,
NOT when your 5 gallon batch of beer will be done.
It's used to measure attenuation of the yeast,
not rate of fermentation.
It will take yeast a lot less time to chew through 12 ounces of wort than it will 5 gallons.....so don't trust that silly thing that someone came up with because they are too afraid to take samples from their beer as being accurate.
If you do take that as "gospel" you more than likely are rushing your beer off the yeast way to soon. You know "bottle Bombs" or suddenly posting an "is my beer in secondary ruined?" thread because now that you moved it to secondary because the "satellite" said it was done, you now have this scary looking growth that you have never seen in your bucket (because the lid is one) that suddenly grew on top of your wort and is ugly as sin....which we of course will tell you to rdwhahb because that is just krausen and it formed because you racked too soon and the yeast is still trying to work to make beer for you.
The idea came from commercial breweries, but you have to realize when they are using in it a 3 or 7 or 10bbl fermentaion setup, that their sattelite looks like this.
And they are drawing off hydro sample out of that bucket just like we do.
And they are STILL going to be taking readings and tasting the REAL beer in the ACTUAL FERMENTER, before making any determination.
It's been adopted by some home brewers, and unfortunately gets perpetuated by people (mostly noobs scared of taking real hydro readings) but it's about as accurate as airlock bubbling, (and you know where I count that in terms of fermentation gauges- slightly below the astrological calender
)
With proper sanitzation you can open up the bucket and take hydro reading with no fear....
Here's what I do....
1) With a spray bottle filled with starsan I spray the lid of my bucket, or the mouth of the carboy, including the bung. Then I spray my turkey baster inside and out with sanitizer.
2) remove lid
3) Draw Sample
4) fill sample jar (usualy 2-3 turky baster draws
5)Spray bung or lid with sanitizer again
6) Close lid or bung
6) take reading
It is less than 30 seconds from the time the lid is removed until it is closed again.
Probably less if you have help.
But don't be in such a hurry to rush your beer to bottles, it's only been 5 days, just becasue the yest may be done fermenting, doesn't mean that their job is done.
How To Brew said:
Leaving an ale beer in the primary fermentor for a total of 2-3 weeks (instead of just the one week most canned kits recommend), will provide time for the conditioning reactions and improve the beer. This extra time will also let more sediment settle out before bottling, resulting in a clearer beer and easier pouring. And, three weeks in the primary fermentor is usually not enough time for off-flavors to occur.
It's no different than our non kit recipes, a beer is a beer, and as you might have read, many of us subscribe to the idea of not rushing our beers off the yeast for at least 3-4 weeks, and find out beers greately improved by doing so. It allows the yeast to clean up any byproducts they created during fermentation, which if rushed away from this process too soon, may lead to off flavors.
Theres' hundreds of threads on here discussing that. So don't rush it, and your beer will thank you for it.