Dumb Specific Gravity Question

I know what specific gravity is (the relation of suspended solids in comparison to zero TDS), and how to use a hydrometer.

But what does it mean if my recipe calls for an original gravity of 1.053 and I got an original gravity reading of 1.043?

Of course people use OG and FG to determine their alcohol content, and I know the equation for determining your ABV percentage is: ABV% = OG - FG * 131.

But my recipe states "check your OG and FG in order to troubleshoot possible problems. Hmmm.

In general it means you did not get the full amount of sugars the reciepe should have produced, don't feel bad we have all been there. A kit using extract almost always gets near the stated OG if the directions were followed.If this were a mini mash or all grain kit or otherwise then its something in your process or the recipe.

If you give us the recipe and all the details of your setup we can point somethings out

Also you problably already know this but temp of the wort when taking the hydrometer reading plays a role

Doh! I didn't record the temperature of the wort. It was a kit, so should I assume that I may just get a lower ABV% since I did not get the full amount of sugars?

Yeah that's right. Do you have any guess as to what the temp of the wort was though? I mean if it was pretty warm when you measured then your OG could be a lot higher.

Corey_SS said:

Yeah that's right. Do you have any guess as to what the temp of the wort was though? I mean if it was pretty warm when you measured then your OG could be a lot higher.

Click to expand...

My room temp is around 69 or 70 F.

There could be a difference of volume. For example, if your kit was a five gallon kit, and you came up with 5.5 gallons, that would account for some of the discrepancy.

hilts said:

There could be a difference of volume. For example, if your kit was a five gallon kit, and you came up with 5.5 gallons, that would account for some of the discrepancy.

Click to expand...

I'm not going to really worry about it too much. My volume should be right at 5 gallons, so if a variation in ABV% exists, that's the least of my potential problems. I'm pretty crappy at carbonating from a CO2 tank lol.

Most hydrometers are calibrated At 68F but the room temp usually does not apply to og because the reading is taken before yeast is pitched and this is before the temp of the wort has had a chance to settle to room temp. Wait and see if the fg is near what the kit calls for

Ok, so final gravity (3 days in a row) is what's really important. Just knowing when the fermentation process is completed.

Let me see if I can clear up a few things. Suspended solids have nothing to do with the hydrometer reading because if they are solid and suspended they must be the same density as the liquid. It's the dissolved solids that make a difference in the density and in beer those should be sugars. You hydrometer is indirectly measuring the amount of dissolved sugars in your wort.

Since you posted this in the beginners forum, I'm going to assume that you started with an extract kit that had you boil the wort and then add top-off water. If that is a true statement, the amount of sugars is already set by the amount of extract. The OG that your really get is the OG that the kit says if you used the correct amount of water. What usually happens when taking the OG is that it reads low because the concentrated wort you added to the fermenter does not want to mix well with the top off water and the hydrometer sample you take has more water than wort giving you as false low reading.

RM-MN said:

Let me see if I can clear up a few things. Suspended solids have nothing to do with the hydrometer reading because if they are solid and suspended they must be the same density as the liquid. It's the dissolved solids that make a difference in the density and in beer those should be sugars. You hydrometer is indirectly measuring the amount of dissolved sugars in your wort.

Click to expand...

Ok, let me clear one more thing up. A hydrometer does in fact measure suspended solids (TSS) as well as dissolved solids (TDS), but what it is truly measuring is density of the liquid in comparison to DiHy H20 when calibrated properly (for dairy, sugars, soils or alcohol) and then compensated for the temperature of the liquid. This is why a person may get significantly different readings if you have not waited at least 24 hours after the liquid (wort or otherwise) has been placed in the container. A laboratory grade hydrometer costs at least $200 while your local HBS will sell one to you for only $10-$12. I have used a hydrometer many times in a soil sampling laboratory at the phD level. Sorry to burst your bubble.