Questions about Taking Samples for Gravity Readings

[mshergold]

Not sure if these questions should be in this section or not (the beer is an extract brew), so please feel free to move it moderators. I brewed my first extract beer last Thursday. The recipe I had was for 19 lires, but I ended up with 10 because I forgot to top up, so when I came to take a gravity reading last night, the hydrometer just sat on all the trub at the bottom of the FV. If I syphon a sample off, would it be OK to pour the sample back into the FV (everything the sample comes into contact with will be sanitised). If I do this, how long would it take for the beer to settle (I guess I might as well ask how long a piece of string is) and would I be better off syphoning the sample back onto the top of the beer to cause less disturbance to the trub?

[Waffty]

Not sure if these questions should be in this section or not (the beer is an extract brew), so please feel free to move it moderators. I brewed my first extract beer last Thursday. The recipe I had was for 19 lires, but I ended up with 10 because I forgot to top up, so when I came to take a gravity reading last night, the hydrometer just sat on all the trub at the bottom of the FV. If I syphon a sample off, would it be OK to pour the sample back into the FV (everything the sample comes into contact with will be sanitised). If I do this, how long would it take for the beer to settle (I guess I might as well ask how long a piece of string is) and would I be better off syphoning the sample back onto the top of the beer to cause less disturbance to the trub?

If you're 110% certain that everything is clean, then in theory, you should be ok to pour it back into the FV but in doing so, make sure you limit any splashes & unnecessary airation. Personally, for 100ml or so, I wouldn't take the risk.

Also, what's the purpose of taking the measurement if the fermentation process has already begun, as it will only tell you the gravity at a snapshot in time? Ideally the gravity should be taken at the begining & end of the fermentation process to (a) ensure the OG is within range (b) to ensure the FG has hit it's target & (C) to ensure that the fermentation process has actually stopped (by getting two identical values).

[mshergold]

Hi Wafty. I'm pretty sure my beer has finished fermenting, so thought I'd try and get to grips with my hydrometer. My OG was 1.054 at 34c (I think after correction it works out at 1.059). The estimated OG in the recipe was 1.042 and the estimated final gravity 1.011. Is there any way I work out what the final gravity should be, or should I be using my favoured method of "weeeeeelllllll, it looks like it's finished fermenting"

[Waffty]

Hi Wafty. I'm pretty sure my beer has finished fermenting, so thought I'd try and get to grips with my hydrometer. My OG was 1.054 at 34c (I think after correction it works out at 1.059). The estimated OG in the recipe was 1.042 and the estimated final gravity 1.011. Is there any way I work out what the final gravity should be, or should I be using my favoured method of "weeeeeelllllll, it looks like it's finished fermenting"

I think you can take the attenuation percentage of a given yeast & try to guestimate your final gravity i.e typical attenuation is 65 to 77%, so on a best case senario, 77% of 59, is 45 points giving a FG of 1013, so I think 1.011 is a little optimistic.

If in doubt, leave it i.e 10 days in a FV won't hurt anything

[boingy]

When you think fermentation has finished start taking daily hydro readings. When the reading is the same for two days running and within a few points of your estimated FG then fermentation has done. Anything below about 1015 is fine (Boingy risks offending the purists... again).

[mshergold]

Hi guys. I just thought I'd let you know that my beer appears to have fermented out at 5.6%. Thanks for your help.