Stuck fermentation - robobrew?

[stav]

hi all,

bought a robobrew a month or two ago and have done 2 brews on it now..
both brews, seem to have stuck during fermentation.
1st one, OG of around 1.040 it only got down to 1.030 - using a white labs ale liquid yeast, tried giving it a swirl, putting the temp up a couple of degrees, a second pack of yeast, and even then made a separate starter, transferred it to a different fermenter and added the starter.. it still wouldn't budge!
The 2nd brew - came out with an OG around 1.045, again, pitched a whitelabs ale yeast.. it started off fementing well, but has now been stuck at 1.025 for a few days..
in 5 years of brewing, ive never had a stuck fermentation before, thinking that it must be something to do with the process i'm using with the robobrew. there is only two real differences in my process now, 1. using the pump to recirculate during the mash and 2. using the wort chiller to drop the temp down after the boil.
has anyone else had similar issues after using the robobrew? there didn't seem to be any threads indicating that.

any ideas what might be causing it? or how to save this latest brew?

cheers,
stav

 

[mattyh77]

Ive got the Robobrew with inbuilt pump, never had this problem before. Done 6 brews through it now.
Ive done one brew using chiller and the rest no chill.
OG has vared between 1.0454 to 1.067. All gotten down to expected FG, using Dry yeast only (re-hydrated).
What are you brewing; recipe, amount of water for the mash, and amount sparging, temp etc?

Onl;y thing I can think of is fermentation temps and yeast used.

 

[manticle]

Are you measuring gravity with a refractometer?

 

[Sidney Harbour-Bridge]

What were the mash temperatures, did you verify that you hit them with a thermometer or read off the robobrew display?

 

[Vazerhino]

i have done about eight brews on the robobrew. i had a stuck fermentation and posted about it here. I always use a separate thermometer for temperatures - the RB is supposedly unreliable and this is certainly the case from my experience with the temps being at least a few degrees off (but that is at the top of the mash).

I didn't think it had anything to do with the robobrew, but rather the fermentation itself. Mine was probably that it was fermented outside my fermentation fridge so got too low temperatures at night. I tried to "unstick" the fermentation using suggestions of Manticle, but it only shifted slightly.

 

[stav]

thanks everyone for the replies. Mash temps were 67/68, with the re circulation on, then sparging with water temps around 73.
thinking back, I'm pretty sure that I used a thermometer to check the temps, but I think it was only at the start of the mash, not continually. was relying on the robobrew to manage it..

grain/water was about 4.5 - 5kg grain to 14-16L water...

yep measuring gravity with a refractometer...
only thinking its the robobrew, or a change in the process as ive never had an issue previously...

what sort of temp would the mash need to be at to cause an issue like this?

 

[manticle]

Are you correcting for the presence of alcohol when using the refrac?

Compare with hydrometer and you may find it's finished. Refrac + alcohol = high reading

 

[stav]

Are you correcting for the presence of alcohol when using the refrac?

Compare with hydrometer and you may find it's finished. Refrac + alcohol = high reading

You sir, are brilliant....it had been a while since i had brewed before getting the robobrew, and prior to that i had only used my refractometer once... just grabed the hydrometer out and checked. sure enough this latest batch has actually finished fermenting, right down around 1.012 where it should be.

Thanks so much, luckily I kjegged the other brew as well!

 

[manticle]

It is a really common error. There are charts that assist with correction - or use refrac for pre-fermentation only and hydrometer for during/post.

 

[Matplat]

We should have a note posted on the front page of the forum about this.... lost count of how many times it has come up!

 

[gil.turcotte]

Are you correcting for the presence of alcohol when using the refrac?

Compare with hydrometer and you may find it's finished. Refrac + alcohol = high reading

OMG! May I kiss you? I was scratching my head with the same issue for months. My last batches FG were so high and I couldn’t find what was the problem. At the end it is just a bad reading! Refractometer 1.031 vs hydrometer 1.004 !!! Pretty high alcohol content.... 8.66% with 94% attention. Next time I will be less stressed about putting all winnings conditions together for a great fermentation. O2, starter, controlled temp... then using the wrong tool for reading FG !?! We always learn something!