Author Topic: When to start checking OG  (Read 974 times)

Offline FLbrewer

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When to start checking OG
« on: May 08, 2013, 07:28:08 AM »
Currently fermenting an American Wheat ale (extract) only using primary. 1) When should I start to check OG?
2) OK to use auto syphon to get the beer out to check (turkey baster won't fit into the carboy)?
3) OK to drink my sample?
4) once it has hit the target OG is there any point in keeping in the fermentor any longer?

Offline tcanova

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Re: When to start checking OG
« Reply #1 on: May 08, 2013, 07:36:26 AM »
Currently fermenting an American Wheat ale (extract) only using primary. 1) When should I start to check OG?
2) OK to use auto syphon to get the beer out to check (turkey baster won't fit into the carboy)?
3) OK to drink my sample?
4) once it has hit the target OG is there any point in keeping in the fermentor any longer?

Just to be clear, if it is in the fermentor you will be checking for FG (final gravity)  OG is measured when it goes into the fermentor (Original Gravity) and is the starting point.  FG is the ending point.

2.)  Yes, just make sure it is sterilized.
3.)  Absolutely!
4.)  Yes, but depends on yeast strain.  Once FG is reached the yeast can still clean up some off flavors, that is where the tasting comes in.  8)
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Offline erockrph

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Re: When to start checking OG
« Reply #2 on: May 08, 2013, 07:39:45 AM »
You're looking for FG, not OG (OG= original gravity, FG = final gravity).

Depending on the starting gravity and health/quantity of yeast pitched, the beer could be finished in a matter of days. Still, yeast will continue to clean up fermentation byproducts for some time afterwards. I leave all my ales in primary for 2 weeks (longer for gravity > 1.070ish) as a matter of procedure. You could probably get away with as little as a week for a lower-gravity brew, but I encourage you not to rush if you can afford to leave it in primary longer.

You could use an autosiphon, but you should consider investing in a beer/wine thief. Just make sure everything is sanitized.

Definitely taste your sample (just don't pour it back, obviously). It will change a lot once it is bottled/carbonated/aged, but you should taste as much as you can at each point in the process. Also, if you pick up any diacetyl (butter/butterscotch) or acetaldehyde (green apple), you know the beer needs more time on the yeast cake to help clean those up.

Once it hits FG, it can generally use some more time to let the yeast clean up some fermentation byproducts. Yeast may be done fermenting sugars in as few as a couple of days, but they will continue to break down other byproducts for a little time afterwards.
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Offline FLbrewer

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When to start checking OG
« Reply #3 on: May 08, 2013, 07:46:58 AM »
FG, FG!

Offline FLbrewer

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When to start checking OG
« Reply #4 on: May 08, 2013, 07:52:31 AM »
Sadly I didn't check OG, but the recipe did include that number (1.043). So how would I know which FG to look for? The instructions mention 2 weeks primary, 2 weeks bottle.
*also mentions the "foam" will fall back into the beer once ferm is complete. 

Online morticaixavier

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Re: When to start checking OG
« Reply #5 on: May 08, 2013, 07:57:20 AM »
Sadly I didn't check OG, but the recipe did include that number (1.043). So how would I know which FG to look for? The instructions mention 2 weeks primary, 2 weeks bottle.
*also mentions the "foam" will fall back into the beer once ferm is complete.

you will know (or at least be fairly sure) you are at terminal gravity when two readings are the same over a period of a couple days.

test, wait 2 days check again, if it is the same.
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Offline HoosierBrew

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Re: When to start checking OG
« Reply #6 on: May 08, 2013, 07:58:56 AM »
You will only have one FG for this beer.  You will know it's final when you get identical hydrometer readings for 2-3 successive days.  It'll probably be there in a few days.  But get in the habit of leaving the beer in primary for the 2 weeks as previously mentioned.  The yeast will clean up after itself, and give you much better beer.
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Offline a10t2

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Re: When to start checking OG
« Reply #7 on: May 08, 2013, 08:14:27 AM »
Good advice all around, but I wanted to add one thing: it's fermentation that drives the schedule, not vice versa. Two weeks is probably a good, conservative guideline, but if fermentation was otherwise healthy there's probably no benefit to waiting that long. Assuming normal pitching rate (one pack/vial in 5 gal doesn't count) and temperature control, an average-gravity ale should ferment out in about 3-6 days. 3-4 days of warm conditioning afterward will probably be beneficial, but after that it should be ready to be crashed and/or racked.

Bottom line, get in the habit of taking gravities every few days throughout fermentation, and you'll have a far better handle on how your chosen yeast strains perform in your brewery. And definitely get one of these: http://www.midwestsupplies.com/fermtech-wine-thief.html
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Offline denny

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Re: When to start checking OG
« Reply #8 on: May 08, 2013, 08:19:51 AM »
FG, FG!

Actually, you're looking at SG (specific gravity) to find out if you're at FG (final gravity).  OG is where it starts, FG is where it ends, SG is both of those and everything in between!
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Offline FLbrewer

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When to start checking OG
« Reply #9 on: May 08, 2013, 08:20:38 AM »
So whether or not I see duplicate readings this weekend (will be one week Sunday) just wait 2 weeks anyways?

Offline FLbrewer

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When to start checking OG
« Reply #10 on: May 08, 2013, 08:21:51 AM »
Assuming normal pitching rate (one pack/vial in 5 gal doesn't count)

Can you elaborate on this?

Offline denny

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Re: When to start checking OG
« Reply #11 on: May 08, 2013, 08:22:31 AM »
So whether or not I see duplicate readings this weekend (will be one week Sunday) just wait 2 weeks anyways?

I would.  To me, there can be a difference between reaching FG and the beer being "done".
Life begins at 60.....1.060, that is!

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Offline a10t2

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Re: When to start checking OG
« Reply #12 on: May 08, 2013, 08:27:52 AM »
Assuming normal pitching rate (one pack/vial in 5 gal doesn't count)
Can you elaborate on this?

The (debatable) standard pitching rate for ales is 0.75 million cells per milliliter, per degree Plato. Higher for high-gravity ales and for lagers. For a 5.5 gal (~21 L) batch at 1.048 (~12°P) that works out to:

21 L * 12°P * 0.75 billion/L-°P = 189 billion cells.

Since a fresh pack/vial contains around 100 billion cells, you'd need to pitch two (or make a starter) in order to get a "normal" fermentation. When under-pitching, it would be expected that fermentation would take longer.
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