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I have an ongoing infection in my beer.


Has anyone ever encountered a fermentation like the pictures attached? Over active fermentation, yeast coming out through airlock, viscous bubbles resulting in a bitter, long lasting, aftertaste?


This has happened in 3 of my last 4 brews.


I have made about 55 AG beers and not encountered it before. Sanitation with Star San, this is the third different fermentor I have tried.


All three brews have been low colour predominantly Gladfields Pils/Pale Ale to make a Cream Ale, 75 minute boil, OG 1.046-1.048. Measured OG pH in last beer and it was high at 6.0. Pitched approx. 20g US05 (two new packs), rehydrated at 23 degrees into 24L.


Fermenting at 17 degrees to get a clean flavour (haa!), fermentation begins fine then on day three the krausen begins to rise and by day six I have what you see in the picture.  


Not looking forward to another 6 hour brew day to then unceremoniously (and angrily) dump it.


Please help as I’m afraid that the rest of my life may be filled with cheap commercial swill…  

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It looks like a healthy ferment to me. Off flavours, especially astringent/bitter can come from over sparging or sparging too hot and extracting tannins.

Also what hops did you bitter with? High cohumulone hops can give a sharper, longer lasting bitterness. Any whirlpool hops or hop stand that might have extracted more IBUs than expected?

Hi Tom,

Thanks for your feedback. 

Brewed 50 All Grain brews before issues occured. Still stumped on this one, have tried different water, bleached all equip, different yeasts, brand new hoses, brewed outside and no change.

Brewed a can of Coopers Lager two weeks ago and have the same off flavours, stalling of ferment at 1.020. It's a real head scratcher, don't know what to do next.

Your femrentation fridge, what is your heating source? and where is it in relation to the fermenter?

For your ferments try pitching at a lower temp and set your thermo to 19, then rise at 3 days to 21-22 

Pitching high and letting it fall to the recommended temp, can cause diacetyl, which can also casue overlasting long bitterness. 

Try this.

1- pitch at lower than your set ferm temp

2- set your temp to around 19 degrees, and let it sit for max 3 days, then raise to 21-22, and let it sit for the remainder of the fermentation.

3- dryhop at your specified time, makingsure your hops are fresh, and kept cold before using. then cold crash for 48 hours keg, fine(if thats what you do), carbonate and enjoy.

Basically your diacetyl pre-cursors are too high, and your missing the D-Rest to help minimise it.

so pitch low, let it rise, do your d-rest early and keep it high, for the total ferment

Hi Rob,

Heat source is a heatpad  inside fridge but not under fermenter (leaning against fridge wall).

Fermented Coopers Lager at 18 degrees, stalled at 1.020 (this is happening with all brews), ramped up to 22 degrees over three days, FG 1.016. Same taste, no crispness and a bitter aftertaste.

Fairly sure it is not diacetyl, no buttery flavour, providing constant relatively low ferm temp and following similar fermentation process of 50 perfect beers. Do a D rest as a matter of course for all beers. Not sure how diacetyl would begin now if it hasn't before.


Bitter aftertaste? 

If your sure its not the D, then I'd say you've got an ongoing infection somewhere in your system. ball valves counter flow chillers etc.

alternatively, i was gonig to say see about your hops etc, but if your coopers lager is the same then i cant say that.

if i was you, I'd suggest stripping your system completely and soaking all the small parts in sodium percarbonate. remember how the bit go together though hahaha.

when i say strip i mean remove the valve and strip the valve where you can, things like that, replace and change seals.

i assumeyour kegging, so it could be in your keg as well change your selasn and strip it, checking for particles in your tubes and lines. (replaceyour beer lines as well)

i also notice you're in a plastic bucket.

I'd suggest replacing it. get a SS one or a carboy maybe? its possible you've got a minimal scratch, which is holding some form of bacteria.

oh and i'd also suggest trying to actually identify the flavor your getting. a bitter aftertaste is quite broad.

taste your beers and describe what your tasting

plastic - metal/blood - tart/sour - astringent (overly dry) - green apples - butter - oversweetness - yeast bite - grainy - salty

Hi Rich, two questions - are you kegging? And what does it taste like when you transfer from the fermentor?

I had an issue like yours where I was getting diacetyl real bad every few brews, after many successful brews. Spent ages on fermentation etc before I finally tracked it to one of my kegs. I found there was a weld repair on one of the internal seams which must have been holding the bugs - even with severe cleaning and sanitation (I wrecked one last brew to prove my theory....) that keg was retired, no issue since.
Lesson learnt, some things just can't be cleaned.
Sorry, should have added it always tested good going into the keg, the badness always developed over time.

Hi Dave,

I get the off flavour out of the fermentor. Over time in the keg it seems to dissipate, but is still there. I'm thinking a wild hard to kill yeast is in the environment and now in fermentors. Did try a new fermentor at one stage and I think that I had a good beer out of it (didn't write in my brew notes which fermentor I used). Regardless I getting bad beers out of that one now too...

not knowing what your process is for fermentation all that much and saying the flavor tends to condition out, i'd say give it an extra week at the elevated temperature. this might help eliminate any possible fermentation issues.

i'd also suggest resting at the higher temp a day earlier just to be sure. that'll remove the majority of any possibility of the big D as well

but a new bucket would be a safe bet (the SS brew bucket might be a good plan?)

Hi All,

Thanks for your responses and ideas.

In the end I emptied out my entire garage, cleaned every surface, put on a haz suit sprayed the entire place with a strong bleach solution, biffed all equip used after the boil, bought new fermenters, hoses etc and problem solved.

Still don't know what it was but would have to hazard a guess at a wild and very virulent yeast.



Are you back brewing now Richie? I did the Mike's Taranaki IPA recipe on fathers day yesterday, hoping for good things.




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