I’ll try my best to describe this although I’m a novice Homebrewer so hopefully I’m using the correct terminology. Buddy of mine has been homebrewing for many years. He now has an all grain setup and has done at least 10 beers off of it. This time we were making a German Roggenbier (Weihenstephaner yeast, rye based Hefe basically) He uses a blow tube on his fermenter and lets the tube drop down into a bucket of sanitizing solution. At the very end my friend did a cold crash and it created a back siphon effect and all of the sanitizer solution got sucked back up into the fermenter. Had to dump an 11 gallon batch. Does this sound familiar or anyone hear of this happening before?
Yes, happens all the time. I’ve tried extending the blow off tube to minimize this (as long as ten feet). Even if the liquid isn’t vacuumed that far, I do not doubt that oxygen is still getting through.
Yes. This is due to volume shrinkage of liquid creating a vacuum effect in the fermenter. Warm liquid expands, cold contracts. To avoid this in the future you will have to figure a way to pressurize (safely) the fermentation vessel. For carboys, some have had luck filling a balloon with CO2 and the attaching it to blowoff. If you have a SS or plastic vessel that can hold 1-2 PSI, that will work as well.
The other option is not conduct a cold crash since it is not a requirement to do so. I have homebrewed 450+ batches and not once conducted a cold crash. Cheers!
I'm assuming primary fermentation is done. I switch the blowoff, and put a regular 3 piece airlock in it to cold crash
This does happen from time to time. If you should ever be using a three piece "dancing hat" air lock it one of the one piece bubblers it is good insurance to add a bit of vodka to the airlock. Helps me sleep better knowing that the water is sanitized should it be sucked in. Cheers
I think I see where Gorm is going with his question, if it was a pint of starsan water in 11 gals of wort he might have dumped too early. It might have been just fine. I'll probably get blasted for telling people to drink starsan, because you shouldn't. But in this case it might have been just fine.
And or if one puts the blow off tube say a inch under a 3 inch deep Quartz container and are using a 1 inch diameter tube, yes some air, maybe starsan, but as well, may b ok.
Yeah... assuming the sanitizer was StarSan, I’m quite certain the batch should not have been dumped. Learned that one the hard way, I guess. Still, I want to minimize the amount of sanitizer I drink too, so there are some ways to avoid “suck back”, and which method works best depends on your setup (mostly what type of fermenter you have). Glass carboys cannot hold pressure! Solid bung or S-type airlock - the airlock will allow air in, but not sanitizer. The solid bing will not allow either in, but you fermenter needs to be able to hold negative pressure. Double blow off jar setup - run a hose into a sealed jar of sanitizer, then another hose from that jar into another empty jar. The co2 from fermentation will fill the first jar, displacing the sanitizer. When you cold crash, the co2 will be sucked back in instead of sanitizer. Balloon - toward the end of fermentation, replace your airlock with a balloon. It will fill with co2, which will get sucked back in when you cold crash Bottled co2 - rig up a system to pressure use your fermenter with co2 to a low level (1-2 psi) so that more co2 will be added as you cold crash. This obviously requires a fermenter that can hold pressure without leaking. Really long/thick blowoff hose - more volume inside hose, more co2 stays inside it. I’m sure there are other methods too. Or you could just not cold crash, like @JackHorzempa stated.
Thanks for the feedback. I will try the ideas, I am glad bubseymour asked the question. By the way, it was 3 to 4 gallons of sanitizer that I had been using in a bucket. So, no chance of salvaging batch.
You had 3-4 gallons of sanitizer pulled into the fermenter? That’s not simple suck-back; you had to have gotten a siphon effect going or something. The volume reduction of the air/beer inside the fermenter due to temperature reduction would not amount to 3-4 gallons of space. Was the fermenter lower than the end of the tube in the bucket of sanitizer? I would definitely recommend not using such a large amount of sanitizer in your blowoff rig; a Mason jar will do. That way, even if you have the issue again, you’ll only pull that limited amount in (maybe along with some air, but that’s not the end of the world) and should be able to salvage the batch. EDIT: Also, if you have 3-4 gallons of headspace in your fermenter, that may not be ideal. I definitely wouldn’t think you’d need a blowoff tube with that much headspace, anyway; a simple airlock should work just fine.
Yeah, I need to make some adjustments. I typically just use the sanitizer that I have leftover and leave it in a bucket. No question about the siphon, the only way to explain it. But it was weird, I was kinda shocked. It is a pretty big fermenter but I still have some active blowoff, especially with Weihenstephaner yeast, it was pushing foam out the 4-foot blowoff tube at one point. I will get a longer blowoff tube and make sure my bucket is much lower next time. They were similar in height this time. Typically, I finish off for a couple of days at about 80 degrees and then crash so I get less muck in my kegs. It only really takes about an hour to get down to 36-40 degrees and then I leave it to sit for a day or so. Can I just leave the hose hanging for that hour while it gets down to temperature? And then put it back in the bucket, that should avoid siphon effect and minimize oxygen I guess.
Since you should no longer be in the fermenting stage when you cold crash, I plug my SS fermenter with a stop. When I get ready to rack, I have a CO2 bottle at the ready with a hose and 4 psi. As Im pulling the plug I put the hose in hole. The inert gas moves in and pushes out any oxygen. Very little oxygen contact .
