confused with the FG reading on mexican cerveza

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tropicalpalmtree

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my OG reading was 1.030, took first final gravity reading today and got solid 0.987, i took several readings a just to make sure it was correct.

according to volume calc's this is saying the brew is 5.6% by volume, which is substantially higher than what its supposed to be (not that i'm complaining lol)

is it normal for the beer to spike in ABV like this? also with the FG being this low would that mean that fermentation is finished? (ill be taking more readings in the following days anyway)

thanks
 
i thought the OG was really low also so maybe the hydrometer is iffy, but having such a low FG made me think that atleast proportionally it was giving me correct info?
 
Float it in some water and see what reading you get. That final gravity is pure cray.
 
just did it again with the water, it does float, but just the red spike bit on the hydrometer out of the water (if you've seen the coopers ones)
 
just did it again with the water, it does float, but just the red spike bit on the hydrometer out of the water (if you've seen the coopers ones)

You'll have to describe it a bit better than that. Chances are that the scale has slipped inside the float, a beer kit will usually be 1012-1008 - no way it's below 1 as that is water.
 
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If you used kit can plus enhancer and the volume of the brew was 23 litres the OG would have been about 1.039ish. That implies an initial error of 0.009. As darrelm has said your FG should be about 1.008 to 1.0012, so assume its finished at 1.010. If you apply the same 0.009 correction your hydrometer should be reading 1.001 in your fermented beer. But it isnt its a lot lower. My suggestion is to scrap it and if you have Wilko near you buy one from there.
Otherwise leave it another week as you first said and by then the chances are it will be properly done. If its clear or nearly clear at that time thats a good sign its finished too.
 
yeah the volume was 23L!

wilko not too far away ill drive up and buy one maybe monday, should i wait another week before adding the dry hop then i presume?

thanks
 
Best I can suggest is to dry hop tomorrow. Leave it four days in the warm. Then move to the coldest place you have for two more days then bottle it next Saturday. I would have at least one bottle in PET so you can monitor how its carbing up given the slight uncertainty about the FG.
 
If you shake the hydrometer does it have liquid in it? Looking at it maybe water got in through the joins between the red and white bits. As it's pretty useless I'd try an take it apart, see what's up and try putting back together.
 
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