taking OG to see if fermentation is complete

[Inkdrop]

I have been brewing a few months now, but up until now, I have only done ales. Usually I ferment in my primary for about a month, and then bottle. I keep reading, where everyone says to take SG readings and you are through fermenting when you have the same SG reading for two of three consecutive days. I am gearing up to do a lager, and I will have to do this so I can check my SG when I am about 2/3 of the way fermented so I can pull my fermenter out of the fridge for the diacetyl rest.

My question is.... is there a specific way to do this? Can I just pull the lid off of my bucket and put a hydrometer in there? Won't that mess up the fermentation by possible allowing bacteria or oxygen in? Do you have to pull a sample with a wine thief and check it in a tube?

 

[DocScott]

You can do either way you suggested. Easiest way in a bucket, is to sanitize your hydrometer and put it in the bucket, take reading, remove it and reseal. This is nice bc you don't lose any volume and it takes 20 sec.

If you want, you can also take a sample w a t sanitized wine thief or turkey baster and read it in a cylinder.

Both ways involve putting something into your beer (sanitized however) which could increase infection chances, but does so in such a small amount, it shouldn't ever be an issue.

 

[RM-MN]

Use a sanitized wine thief or a sanitized turkey baster to take a sample and put it in a tube to read. Your CO2 is heavier than air so it won't escape while you have the lid off unless it is windy or you stir it up. Don't put the hydrometer in the bucket, it is nearly impossible to read correctly in there.

 

[JLP]

Use a sanitized wine thief or a sanitized turkey baster to take a sample and put it in a tube to read. Your CO2 is heavier than air so it won't escape while you have the lid off unless it is windy or you stir it up. Don't put the hydrometer in the bucket, it is nearly impossible to read correctly in there.

Your talking about waiting until the krousen dies down first right? Outside of that, should have no issue getting a hydrometer reading from putting it straight in the bucket.

 

[RM-MN]

With the hydrometer floating in the bucket it's hard to tell if the reading is 1.018 or 1.016 so when you are deciding if the beer is ready to bottle, that difference can spell a bottle bomb instead of properly carbonated.

There is no real reason to take a hydrometer reading if the beer still has krausen except in the rare instance that krausen doesn't fall. You'd like an OG to determine your efficiency and to decide if you need to add some malt extract to get the amount of fermentables when brewing all grain and a couple readings when you think it is done to verify you have reached final gravity, perhaps more if brewing a big beer to decide if your yeast is still working.

 

[unionrdr]

I use the plastic tube the hydrometer came in for testing. Northern Brewer has this blue disc thing that fits the base of these tubes to make it stand up steady for only $1.60! you can see it in my gadget videos on youtube. Same name there as well.
Give the beer 2-3 weeks to finish & clean up/settle out clear or slightly misty & take hydrometer sample. Wait two days,& on the third day,take the test again. If the numbers match,it's done. Settling out clear or slightly misty means it's cleaned up by products of fermentation & settled them out with the yeast that've broken them down. So you'll get cleaner tasting,clearer beer.
Here's the vid with the hydrometer tube disc;

 

[Inkdrop]

okay, so if I am fermenting in a bucket in the fridge, how often should I pull the lid off to check if the Krousen has fallen? I have to pull it before it has completely fermented for the diacetyl rest. Should I wait until it has finished bubbling, and then pull the lid off to see if the Krousen has fallen, or would that be a bad way to judge it? I don't want to leave it to long and the yeast go dormant and not clean up.

Also, when I rack to my secondary to lager it, how much yeast do I leave in it? Do you need a little bit of yeast in there for the lagering process? or no?

 

[PDX_T]

The diacetyl rest is the most "mysterious" thing about brewing lagers. I can tell you from personal and professional experience though that the D rest can be done at ferment temps, it just takes a few more days, and that you can let the beer warm up for a D rest even if it is closer to FG than 2/3 or 80% or whatever you've heard. The yeast will not go dormant immediately upon reaching FG. Also, you will more than likely have plenty of yeast in suspension to lager if you leave the cake behind. you really don't want that trub getting transferred anyway. That being said, I don't transfer lagers. I just bring the temp down. Good technique, bad technique? It's just what's easiest for me to do, and I'm a bit wary of oxidation, so I'd rather keep the fermenter closed.

 

[Inkdrop]

Thanks for the help!! Much appreciated. So I will just let it ferment for three weeks or so, and then check it to see if ready for the D-Rest.

Is oxydation a big problem when racking to a secondary? I thought that was supposed to be an issue while the wort is hot.

 

[Yooper]

Thanks for the help!! Much appreciated. So I will just let it ferment for three weeks or so, and then check it to see if ready for the D-Rest.

Is oxydation a big problem when racking to a secondary? I thought that was supposed to be an issue while the wort is hot.

No, oxidation is a huge risk, and especially post fermentation. A big headspace is a big risk, as is splashing or otherwise oxidizing the beer.