Stuck fermentation on a Mangrove Jack's kit?

[Twopan]

I have set off a Mangrove Jack's Brewer's series Pale Ale. It's a 1.7Kg kit to which I added a 1.2Kg pouch of light liquid malt extract. Normally I would expect that to increase the fermentation potential of the brew. The kit claims to produce a FG of 1.006 and an ABV of 4.4%.
So, I had trouble getting the brew down to 25 degrees in the summer warmth and delayed pitching the yeast overnight until I was sure it was below 25C. I was surprised that the OG was only 1.037 at most (checked with the ISpindel and my trusty standard glass hydrometer). And that is the temperature-adjusted reading.
It went mad for the first 36 hours and dropped to 1.011. Now it has resolutely stuck at that gravity. Very little airlock activity. I stirred it yesterday to get the yeast moving again and bizarrely, it went up a degree to 1.012, where it has now stubbornly remained for more than 24 hours. Airlock barely moving.
If it doesn't do any more I will end up with a very weak brew of about 3.3%, which will be disappointing considering this is a kit.
So I weighed the yeast sachet that comes with these kits - 5g!! That says to me that it is under pitched as when I make a 20L Belgian pale Ale at 5.5%, I would expect to pitch two 10g sachets of M41 Belgian Ale yeast, to get enough cells in.
To the point: I have a spare identical dried yeast sachet from another Mangrove Jack's kit that I repurposed for my Belgian Ale. Is there any harm in pitching this extra 5g of yeast at this stage to encourage the thing to ferment down to 1.006 i.e. another -6 points? Thanks for your help!

 

[clib]

I have set off a Mangrove Jack's Brewer's series Pale Ale. It's a 1.7Kg kit to which I added a 1.2Kg pouch of light liquid malt extract. Normally I would expect that to increase the fermentation potential of the brew. The kit claims to produce a FG of 1.006 and an ABV of 4.4%.
So, I had trouble getting the brew down to 25 degrees in the summer warmth and delayed pitching the yeast overnight until I was sure it was below 25C. I was surprised that the OG was only 1.037 at most (checked with the ISpindel and my trusty standard glass hydrometer). And that is the temperature-adjusted reading.
It went mad for the first 36 hours and dropped to 1.011. Now it has resolutely stuck at that gravity. Very little airlock activity. I stirred it yesterday to get the yeast moving again and bizarrely, it went up a degree to 1.012, where it has now stubbornly remained for more than 24 hours. Airlock barely moving.
If it doesn't do any more I will end up with a very weak brew of about 3.3%, which will be disappointing considering this is a kit.
So I weighed the yeast sachet that comes with these kits - 5g!! That says to me that it is under pitched as when I make a 20L Belgian pale Ale at 5.5%, I would expect to pitch two 10g sachets of M41 Belgian Ale yeast, to get enough cells in.
To the point: I have a spare identical dried yeast sachet from another Mangrove Jack's kit that I repurposed for my Belgian Ale. Is there any harm in pitching this extra 5g of yeast at this stage to encourage the thing to ferment down to 1.006 i.e. another -6 points? Thanks for your help!

What the brew volume?

 

[Twopan]

23 litres

 

[clib]

2.9kg of LME in a 23 litre brew equates to an OG of 1.038. That can be calculated in advance. You can add more extract and/or sugar to the fv at any point.

With an OG of 1.038 an attenuation of 75% would give an FG of 1.010, so you don't really have a problem - just a low OG.

Another 1.2kg of LME (to get to 1.054), or a kg of beer enhancer (also 1.054), maybe. Even just adding 500g of sugar would lift the theoretical OG to 1.046. Just add something now.

 

[Twopan]

Thanks. I'll try that to cheer it up.

 

[clib]

Thanks. I'll try that to cheer it up.

Before you make an extract brew, plug the extracts and sugars into a brewing calculator, like brewersfriend or brewgr.com

Or, in a 23 litre brew...

1kg sugar provides 1.017 points (500g = 1.008)
1kg dried extract provides 1.016 points (so for example 3kg = 1.048)
1kg liquid extract provides 1.013 points (1.2kg = 1.016 and 3kg = 1.039)

Edit: on the question of yeast quantity, 5g packs do seem small. But I pretty much think that it's more about quality than quantity. Yeast replicates itself by splitting and therefore half the quantity simply adds another life cycle. It keeps doubling until it runs out of food. Healthy yeast won't struggle. There's a limit to this of course, but 5g/6g packs of yeast can ferment 23 litre batches of 1.040 beer without any issues of the yeast is in good nick, in my experience. A pack stuck to a tin in a shop for 6 months, probably not. Buy from a place with a fast turnover, or replace the yeast.

 

[Twopan]

Many thanks for all the advice. I'm learning fast here. I will add 500g of dextrose to the current brew to get me up to an expected ABV of 4.4% and see if it ferments out. I'll watch out for yeast age.

Have consulted the calculators on Brewersfriend - that belies the Mangrove Jack claim that it should produce 4.4%, as your figures above demonstrate that it shouldn't on those quantities. My son (expert brewer now) has bought me a book by John J Palmer 'How to Brew'. Finding it fascinating.

 

[clib]

Many thanks for all the advice. I'm learning fast here. I will add 500g of dextrose to the current brew to get me up to an expected ABV of 4.4% and see if it ferments out. I'll watch out for yeast age.

Have consulted the calculators on Brewersfriend - that belies the Mangrove Jack claim that it should produce 4.4%, as your figures above demonstrate that it shouldn't on those quantities. My son (expert brewer now) has bought me a book by John J Palmer 'How to Brew'. Finding it fascinating.

A good book, everything you need to know.

 

[Twopan]

Thanks - brew back up and running now. Even if it now stops at 1.011, it will be the right strength and should have some body I hope.

 

[Knuckles]

Twopan, I had the exact same problem with the Mangrove Jack's American IPA, I thought it was because I mixed it in my new conical fermenter and maybe the extract had settled in the conical bit and not mixed in properly, leaving me with a lower O.G. of 1.035.......but maybe not...after reading your post. Mine fermented for about 36 hrs and stopped at 1.012.....so I share your disappointment strength wise.

 

[Twopan]

Hi Knuckles! Yes, as clib advised me, if you consult the Brewer's Friend calculators Homebrew Beer Calculators for Brew Day | Brewer's Friend, you see that the amount of extract in these kits, combined with either 1.2Kg pure LME or 1Kg of dextrose, is only sufficient to get the gravity up to 1.039 on 23 litres. If it actually ran down to an FG of 1.006 as stated on the box, this would produce an ABV of 4.3%. But mine resolutely stalled at 1.011 after 36 hours and that would be weak. I took clib's advice, opened the FV, and added 500g of dextrose, giving it a damn good stir to get more oxygen in. Within an hour it was off again and the the gravity now, 18 hours later, is already at 1.009, lower than the 1.011 it stalled at. Admittedly have upped the fermentables, increasing the OG retrospectively to around 1.046. If it finishes at 1.009 it will be an ABV of 4.9% and if 1.006 it will produce 5.2%. So slightly stronger than I had planned for this brew, but better than maiden's water!

 

[clib]

Hi Knuckles! Yes, as clib advised me, if you consult the Brewer's Friend calculators Homebrew Beer Calculators for Brew Day | Brewer's Friend, you see that the amount of extract in these kits, combined with either 1.2Kg pure LME or 1Kg of dextrose, is only sufficient to get the gravity up to 1.039 on 23 litres. If it actually ran down to an FG of 1.006 as stated on the box, this would produce an ABV of 4.3%. But mine resolutely stalled at 1.011 after 36 hours and that would be weak. I took clib's advice, opened the FV, and added 500g of dextrose, giving it a damn good stir to get more oxygen in. Within an hour it was off again and the the gravity now, 18 hours later, is already at 1.009, lower than the 1.011 it stalled at. Admittedly have upped the fermentables, increasing the OG retrospectively to around 1.046. If it finishes at 1.009 it will be an ABV of 4.9% and if 1.006 it will produce 5.2%. So slightly stronger than I had planned for this brew, but better than maiden's water!

Interesting it got down to 1009 - a restart can do that. It may have crept there anyway of course. Hope it turns out ok, should do. The MJ kits are pretty good. 1.038 to 1.006 requires an attenuation of 84%, and not many dry ale yeasts out of a packet will do that. Not reliably anyway. Bit optimistic. I do use kits sometimes but I always work out the stats in my brewing calculator, adding in the extracts and sugars, and I predict the attenuation based on the yeast I'm using. Usually end up pretty close. A good step is to use a bit of grain, as well as adding hops. It's another job but also another improvement.

 

[Twopan]

Interesting it got down to 1009 - a restart can do that. It may have crept there anyway of course. Hope it turns out ok, should do. The MJ kits are pretty good. 1.038 to 1.006 requires an attenuation of 84%, and not many dry ale yeasts out of a packet will do that. Not reliably anyway. Bit optimistic. I do use kits sometimes but I always work out the stats in my brewing calculator, adding in the extracts and sugars, and I predict the attenuation based on the yeast I'm using. Usually end up pretty close. A good step is to use a bit of grain, as well as adding hops. It's another job but also another improvement.

Yes thanks. It seems to be stabilising around 1.009 now, which in reality may be 1.010 allowing for the warm conditions. I'll leave it a few days and then bottle when it's clearly not moving any more. At the risk of boring everyone to death, I'll report back on the final result. I will also try some dry hopping. I was going to do it on my attempt to clone a Belgian Blond but decided against after tasting the thing mid fermentation, as it seemed to match what I was aiming for.

 

[clib]

Yes thanks. It seems to be stabilising around 1.009 now, which in reality may be 1.010 allowing for the warm conditions. I'll leave it a few days and then bottle when it's clearly not moving any more. At the risk of boring everyone to death, I'll report back on the final result. I will also try some dry hopping. I was going to do it on my attempt to clone a Belgian Blond but decided against after tasting the thing mid fermentation, as it seemed to match what I was aiming for.

Once you've started talking about a beer it's always good to follow up with the results.

It's an incomplete thread otherwise!

 

[labrewski]

I've done quite a few mangrove jacks kits and the majority kept going slowly for 3 weeks
But all were well worth waiting for top quality kits in my eyes

 

[Knuckles]

Agreed they are good kits but they dont tell you how much sugar to use for carbonating? Any reason for this?

 

[Twopan]

You're right - I assume because they're trying to sell you MJ's carbonation drops! I always add priming sugar at the racking off stage. I go by the guide table in my John J Palmer brewing bible ("How to Brew"). A 23 litre kit would need c. 158g of Dextrose to prime the racked off brew. Festival world beer kits come with priming sugar and that if I remember correctly is a 150g sachet of dextrose.

 

[Poddyc]

Each to their own, but would personally use less for a Pale Ale. Think 90g dextrose for 23 litres would be plenty (1.8 vol CO2).

I'd only go up to 150g for something like a Belgian or a Wheat, aiming for 2.4 vol CO2.

(Festival kits vary the included priming dextrose, depending on style).

Good calc here...

https://www.brewersfriend.com/beer-priming-calculator/

 

[Twopan]

Thanks! I used 140g for 20L of St Peter's Golden Ale and it came up a bit fizzy. So will check this out.

 

[TrevTheBev]

I just use simple granulated sugar for priming and never once had any problems. 1 or 2 teaspoons of it seem to give great carbonation and a fine head, no matter what I'm brewing. I did once use 3 teaspoons for a cider and that was perhaps a tad gassy...... But still managed to finish it off.