Mangrove Jacks M20 Stalled

[killspice]

I put down a wheat beer nearly 2 weeks ago with the following recipe:

2.5kg Pale Malt (BB)
2.5kg Wheat Malt (BB)
25gm Saaz @ 60m
Mashed at 65.6 for 75m
Mash out at 75 for 10m
I lost ~1.5deg over the 75m
Beersmith OG 1.057, Measured FG 1.060 - it's a bit high because the boil was more vigorous than I intended (adjusted my burner air input valves)
Beersmith est FG 1.015 (with k-97 yeast set to 73% attn. - I figured the "medium" attenuation of M20 would be similar)

No chilled.

1pk Mangrove Jacks M20 Bavarian Wheat @ 17deg, rehydrated as per the general guidelines on the 21st

The yeast took off pretty quickly, with noticeable activity after 12 hours, and a 1-2cm krausen within 2 days.

After 3 days I raised it to 18deg. By Saturday the krausen had dissipated and the reading was just over 1.020. Monday it was still 1.020, so I did a quick swirl and bumped it to 19deg. Yesterday it was still 1.020 so I bumped it up to 24deg with another swirl.

It is currently still sitting at 1.020, so I was hoping for some advice.


I have a few of options I can think of
1) Leave it - at 24deg and wait it out a few more days. If nothing changes then choose one of the other options.
2) increase the temp more - I really don't think increasing it further is a good idea
3) rack it to a secondary and hope it kicks off a bit - with a low flocc yeast and a swirl I wouldn't expect racking to provide much extra stimulation
4) add some simple sugars - how much would one use (100gm in 500ml water?)
5) 3 + 4
6) add some yeast - I have some old kit yeasts (from a coopers ginger beer recently, and 2 others from god knows how long ago - I'm not sure which is which) a Mangrove Jacks M27 Belgian Ale (which I was planning on using on my next beer, seems too good to waste on a cleanup), or wait until I can get my hands on a us-05 (weekend or early next week).
7) 4 + 6
8) bottle it - it tastes alright actually, not overly sweet/cloying even warm and uncarbed, but 5 points off FG seems way too risky (I probably have enough PET but would rather get the FG right than faff around constantly relieving pressure if it is going to fermount out further.

Any thoughts?

 

[NewtownClown]

Are you using a refractometer for your readings?

 

[killspice]

Are you using a refractometer for your readings?

Hydrometer (I double checked I hadn't damaged it since my last brew, still reads 1.000 in water @ 20deg)

 

[spaced]

This yeast has very low attenuation from what I found. Ferments fast but stops pretty high.

 

[killspice]

This yeast has very low attenuation from what I found. Ferments fast but stops pretty high.

Fair enough, apparent attenuation is 67% which isn't that far below the 70% lower bound here: https://www.brewtoad.com/yeasts/22889 so it might just be done.

 

[spaced]

How does it taste?

 

[killspice]

How does it taste?

"it tastes alright actually, not overly sweet/cloying even warm and uncarbed" - basically it has the flavours I expect and although I was going for a drier finish I think it would still be drinkable when chilled and carbed. I don't think I've ever had anything finish > 1.014 though, so when it stopped at 1.020 I was concerned.

 

[ebyelyakov]

I'm guessing 1.020 is the decent max you can expect. Assuming the fermentability of your wort was 85% (that's the best figure one can hope for an adjunct free wort), the 100% attenuation would mean you'r stop at 1.09... 1.02 says the attenuation of your fermentable sugars was 78%

Obviously, the higher you mashed the less fermentable the wort would be.

 

[shacked]

I had a lazy wheat beer last month that took forever to get down to FG. I suggest you do a fast ferment test as per Manticle's article: http://www.aussiehomebrewer.com/articles/article130.html

The fast ferment test will let you know if your yeast has a bit more to go.

 

[Osangar]

I have used this twice, and in both cases it finishes at 1.018. Beer tasted ok. And at a 1.058 og still gives a bit over 5% abv.