Low final gravity

[JohnB]

Hi folks, I've not been on the forum lately, but I have a recurring problem and not sure what to do so I decided to run this past you experts and see what you think. I've hunted around on the forum and most problems posted stem from over-high FG, My problem is quite the reverse all my brews over-attenuate giving me FG's as low as 1004.

I've been brewing several different styles of English Ale, pale, bitter, porter, etc. The problem seems to be that I get continually low final gravity readings, often as low as 1004 on some pale beers.

I have tried yeast from different sources, Nottingham, Gervin from Wilco's, Real Ale from Crossmyloof.

I'm using Marris Otter base malt, carapils, light crystal, extra dark crystal in some brews and a little chocolate in the porter, I even tried brown malt in small quantities in one brew.

My temp controls are now quite good, I can ferment at 20 DegC. with certainty, my mash temps are good, I can hold within a degree or so for 75 minutes, though normally I mash-out early after iodine tests show we're done, often 45 minutes.

I have tried different mash temps, anything from low 60's to as high as 72 degC. on a porter to try to get a sweeter more full bodied taste, but FG ends at 1006 - 1008 when I was aiming for 1012 - 1014. Is there a trick to stopping fermentation, please?

Any suggestions would be most welcomed thank you all.

 

[Cwrw666]

Lot of information there. But you haven't told us if your beers are turning out tasting ok. I must say I've never really noticed any affect on flavour the odd times I've had lower than expected FGs.
Have you checked the accuracy of your hydrometer?
Do you have a general wild yeast infection? They often ferment to a lower FG and also often don't affect the taste noticeably.

 

[JohnB]

Oh dear, yes sorry about that Cwrw666 I guess that is one of the most important parts left out erm ... well, when I first started all-grain I made some rubbish, but practice makes pretty good. No off flavours, I can't be sure about wild yeast, and under the microscope nothing looks odd. I even brewed a porter that got an A-star from a seasoned Guinness drinker. My bitter is spot on both flavour and FG, it's the heavier beers that seem to over-attenuate. I have a pale ale (Burton Pale Ale) on the go at the moment and it is already down to 1.010 and still bubbling away merrily. It smells superb as well.

Is there a specific yeast that might be a bit more appropriate for the heavier beers? I just use English yeast types 'cos I'm trying to brew what might be called English in style. I try to use English hops, EKG, Fuggles, Challenger, Target, and so on.

 

[JohnB]

By the way, I use both a hydrometer and one of those new-fangled refractometer things (during the brewing phase) as a double check and both seem to be within a degree or two of each other. I use the same hydrometer to check at the end of fermentation. Obviously the refractometer doesn't work at that stage.

 

[The Baron]

Also check you temperature is correct at mashing as it could a faulty reading from whatever it is that gives you the temp

 

[Slid]

I suspect that if you once use a high attenuating yeast, like a Saison, or a Belgian yeast like Mangrove Jack-s M31, there is a potential for some yeast cells to perpetuate in the fermenting vessels. Towards the end of the ferment, they may have some opportunity to carry on after your main yeast has got to its limit. There can be very little contribution from this later ferment to the overall flavour profile, just a further conversion of sugars.

I think this has happened with my beers. I am not sure that I necessarily think this is a big issue that I need to sort out, as it is just a few gravity points. As my go-to yeast is the fairly high attenuating US 05, this is actually in line with my own (slightly "low-brow") preferences.