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Airlock vs Blow Off Tube (Limited Space)

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NzBrewerMatt

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Hi guys, I've just purchased a fridge for fermentation and rigged it up with a temp controller. I'm also trying to fit two 30L fermenters in the fridge, one above the other. One is plastic, the other is stainless steel. The only thing I'm currently struggling with is space. I didn't really accommodate for the airlocks when getting the fridge.

I can fit one fermenter with an airlock at the top of the fridge however the airlock is 2mm away from the top of the fridge. Is this too close to the top? The bottom fermenter won't allow me to fit an airlock in unless I push the boundaries and try and angle it somehow.

Question is, would it be better to just use blow off tubes running into a bucket of sanitised water for both fermenters? That way I'd be able to fit the two fermenters in easily and i can ferment more beer.
The fermenters are both 30Litres (7.9 Gal) and I'm brewing around 19-23 Litres (5-6gal) at a time through BIAB.

If a blow off tube is the preferred method, is there a specific size/thickness it needs to be? Does it just need to fit in nice and snug to the bung that goes into the hole on the fermenter?

Also, would you need to replace the sanitised water in the bucket at all or is this ok to remain the same for the full fermentation?
 

mtb

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With that amount of headspace you don't need either unless you're using a yeast with krazy krausen. Glad wrap and a rubber band will do you just fine.
 

Grott

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I’d go the blow off tube for both kegs into the bucket. Wouldn’t have to change it unless it starts to fill. The tube should be a snug fit to the grommet.
 

NzBrewerMatt

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Thanks Mtb for the fast response. So would I just put glad wrap around the current bung? I’ve just been using US-05 and MJ M-44 yeast so far.
 

mtb

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Depends on your fermenter. The point I'm making is that you shouldn't expect any krausen to blow out the top with that headspace, not with US05 at least. See below for example of glad wrapping a bunnings water drum thingy.
It's sealed enough that nasties can't get in, but excess Co2 can get out. No need to overcomplicate matters.
 

NzBrewerMatt

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Depends on your fermenter. The point I'm making is that you shouldn't expect any krausen to blow out the top with that headspace, not with US05 at least. See below for example of glad wrapping a bunnings water drum thingy.
It's sealed enough that nasties can't get in, but excess Co2 can get out. No need to overcomplicate matters.
Thanks mtb.
This is the fermenter I'm using is below.
I can't tell if it has a bigger or smaller opening than yours but i can probably skip the lid altogether and just use glad wrap?
 

NzBrewerMatt

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I’d go the blow off tube for both kegs into the bucket. Wouldn’t have to change it unless it starts to fill. The tube should be a snug fit to the grommet.
Thanks Grott.
Is there a specific size of tubing i should use? I have some 5mm at home but would this be too thin?
 

NzBrewerMatt

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Yep chuck that lid, glad wrap is your friend. Use the rubber seal in the lid as a rubber band.
Awesome, thanks. I’ll give this a go this weekend!

You don’t put any holes in your glad wrap right?
 

earle

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I bought one of these years ago. Wider (45cm instead of 33cm) and heavier than the normal clingwrap from the supermarket. About $30ish but will last me for a long time. Get it from a hospitality supplies store.

 

Schikitar

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I've been thinking about this cling wrap idea and doing away with the lids (I have the same fermenters and a fridge that won't accomodate the traditional airlocks). I believe cling wrap is permeable and I assume in both directions, so is the amount of CO2 in the headspace enough to keep the O2 out? Also, what about at the end of fermentation, does O2 start finding its way in or is a fermenter full of wort/beer always generating enough CO2 to keep it out?

What about when dry hopping, do you just discard and replace? Do we need to sanitise it in anyway or can we safely assume it's good to go when unravelled?

What's the best way to get those rubber seals out of those lids? I've tried but they don't seem to want to come out easily..
 

earle

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First question is a can of worms. My experience is that of no noticeable oxidation of the finished product. Usined this method I have had beers as lightly flavoured as a Kolsch which have placed in the Qld state comp.

For dry hopping i remove the o-ring, lift up an edge of the cling wrap and tip the hops in, carefully place the lifted edge of wrap back down and replace the oring.

I have used a kitchen dinner knife (not overly sharp) to remove the oring. You only have to remove it once.
 

2cranky

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I use an upright freezer and can just fit 2 fermenters in there. I tried the glad wrap and I didn't like it (probably because I can't see anything going on).
So I use a blow off tube. Just get 8mm OD (I think) clear PVC tubing from Bunnings and a clear bottle of some sort.
ferment.jpg

either way will work though.
 

earle

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I tried the glad wrap and I didn't like it (probably because I can't see anything going on).
Each to their own of course but this is one of the things I like about glad wrap - very visual. You can look in and see the krausen and what's happening on the surface whetehr it be yeast, hops or bubblesof gas. During active ferment the cling wrap will bulge upwards from the gas pressure, as fermentation finishes the cling wrap drops back down.
 

NzBrewerMatt

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First question is a can of worms. My experience is that of no noticeable oxidation of the finished product. Usined this method I have had beers as lightly flavoured as a Kolsch which have placed in the Qld state comp.

For dry hopping i remove the o-ring, lift up an edge of the cling wrap and tip the hops in, carefully place the lifted edge of wrap back down and replace the oring.

I have used a kitchen dinner knife (not overly sharp) to remove the oring. You only have to remove it once.
Thanks for the tips Earle.
In regards to dry hopping, are you just dropping the hops straight in or are you sneaking a hop sock in under the glad wrap?
 

earle

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Thanks for the tips Earle.
In regards to dry hopping, are you just dropping the hops straight in or are you sneaking a hop sock in under the glad wrap?
Just dropping straight in. I find most of them drop out during the cold crash.
 

2cranky

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Each to their own of course but this is one of the things I like about glad wrap - very visual. You can look in and see the krausen and what's happening on the surface whetehr it be yeast, hops or bubblesof gas. During active ferment the cling wrap will bulge upwards from the gas pressure, as fermentation finishes the cling wrap drops back down.
Yeah that's my point. I only get about 40mm above each fermenter in there so I can't get over it to see in. So Blow off works best for me.
 

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