# Blowoff Suck Back



## Bribie G (22/9/17)

No, the title of this thread didn't accidentally miss out "babes" or anything so settle down chaps.

With my SS Brewbucket I'd been using an old fashioned two piece airlock, but since San Diego Super Yeast came back I've been doing the following "blowoff" arrangement, as a precaution (not needed as it happens);






As you can see, a 1.25L springwater bottle half full - with springwater as it happens, just drain of half for kitchen use then pop the hose in.

This works fine, perfect seal on the lid and bung so it's a good method of monitoring progress as I can't see into the FV and fairly kitten proof.

Now after the bloops subside to one every half minute or so I've been reducing to near zero for a week then transferring into a CO2 filled keg. Last three brews the blowoff bottle has been empty on keg transfer.
First two times I thought "strange".
Yesterday the penny dropped, as it should have done, and I thought "****, Bribie, how could you have missed that one".

Clearly on cooling, the volume of the beer has decreased and also the volume of the gas in the headspace - I mean the volume occupied by the molecules of the gas - and there has been "suck back" - to the tune of about half a litre per brew in this case.

No deleterious effects on the beers that I noticed - there has been some slight dilution of course but I've escaped infections as the system has been pretty sterile to begin with. I'm just concerned that after the suck back of the water, then some air would probably been sucked in as well. Nasty 02.

Solutions?

1. Removing the bottle prior to cold conditioning in the Brewbucket would result in the same amount of air being sucked back in. Not good as I'm on a reduced oxygen regime.

2. Transferring to intermediate cold conditioning keg in a non-02 environment would work but double handling and loss of beer.

3. Collecting CO2 into bag towards the end of fermenting and letting this get sucked back into headspace of FV.

I tend to go with #3 and looking at attaching a bag (e.g just large common freezer type bag) tightly taped to end of hose. Fermentation slows to a crawl, bag slowly inflates, then deflates as gas later sucked back in. We only need about a litre capacity I'd guess.

Fermenting under pressure in a closed system? Yup got all that already, with a modified cornie and a spunding valve, just talking about using a Brewbucket. And of course this situation would arise with most other FV types used to cold condition in FV including cling wrap.

Anyone done anything similar?


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## TidalPete (22/9/17)

I’ve found that a larger diameter blow-off tube (combined with a half-full 3-litre juice container of boiled water) works well. especially when using top-cropping yeasts where you want to save the (blown-out) yeast but that’s a subject for another thread.
Just a two birds\one stone sort of thing.

Upon fermenter volume shrinking due to the cooler temps, the larger volume of air in a (bigger diameter) blow-off tube is much more resistant to suck-back than a smaller diameter tube used in conjunction with a normal ½” airlock.

Of course, with the BB only holding 26 litres against say, an ss olive oil brum of 32+ litres, it stands to reason that a bigger diameter blow-off tube is more advantageous in that situation.

My 2-cents.


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## Moog (22/9/17)

i always use starsan in my airlock, when I re-set for cold crash, I empty the airlock, and replace with a wad of cotton wool, a tip I read off the net, the cotton wool is sterile, and acts as a filter to clean the air going in, works good, not had any infections, although neither did I when I used to get starsan sucked back in.


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## micbrew (22/9/17)

you have my full attention  OH FERMENTATION !


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## mtb (22/9/17)

A non-return valve in that blowoff tube? You'd end up with a vaccuum in your Brewbucket though..
ed: How about this - non return valve inline on your blowoff tube. At the end of the blowoff tube, a gas disconnect. During fermentation the blowoff disconnect is connected to a carbonation cap and flows into the springwater bottle as normal, not sealed.
When you start the cold crash, disconnect the gas DC. Vaccuum forms in the Brewbucket and the blowoff tube.
On kegging day, connect the gas disconnect to your CO2 filled keg to allow CO2 to flow in and negate the vaccuum. Pull the PRV to finish bringing the Brewbucket back to room pressure, you'll get some O2 ingress to the keg and assumedly the blowoff line but hopefully it'd be negligible.

I've heavily overengineered that and there is likely a flaw, such is the case after a six pack of 4 Pines Pale Ale in memoriam


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## TidalPete (22/9/17)

mtb said:


> A non-return valve in that blowoff tube? You'd end up with a vaccuum in your Brewbucket though..



That's been done with not-so-good results.


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## Kev R (22/9/17)

I use a filter housing with the filter removed, a stainless tube from the centre of the lid to the bottom of the housing.
The blowoff goes in top, forces starsan out the tube into a container. When crash chilled it reclaims the c02 from the filter housing and suckes the starsan back into tbe filter and not into the brew.
Not sure if putting the expelled c02 back in to the fementer is good or bad, doesn't seem to have caused any problem.


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## Danscraftbeer (22/9/17)

I dont understand how it could get sucked back? Easy solution is to pull the blowoff tube to above the waterline or just disconnect it at end ferment.
I pressure ferment btw. It only goes one way and that is out. Even when I've used a mini keg to collect blow off yeast its all one way. Disconnect if your worried about suck back.
I've never experienced this suck back scenario.


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## fdsaasdf (22/9/17)

Danscraftbeer said:


> I dont understand how it could get sucked back? Easy solution is to pull the blowoff tube to above the waterline or just disconnect it at end ferment.
> I pressure ferment btw. It only goes one way and that is out. Even when I've used a mini keg to collect blow off yeast its all one way. Disconnect if your worried about suck back.
> I've never experienced this suck back scenario.


It happens when you chill, and if you seal the stainless vessel you risk imploding it.


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## Bribie G (22/9/17)

As I posted in the OP, my worry is that if I just pull the tube out of the "airlock" fluid it's going to suck back air = oxygen.


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## Danscraftbeer (22/9/17)

I'm still confused as to how 500ml water gets sucked back into your brew? 
All being in the same temperature control I cant understand how it could happen.


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## Brewno Marz (22/9/17)

Is there a number 4? No cold crash, just keg and accept the great, but bit cloudy beer, you've made.


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## Danscraftbeer (22/9/17)

fdsaasdf said:


> It happens when you chill, and if you seal the stainless vessel you risk imploding it.


Implosion? Not an issue to consider.
Re- pressure ferment. It all goes out, nothing goes back in.


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## Brewno Marz (22/9/17)

Danscraftbeer said:


> Implosion? Not an issue to consider.
> Re- pressure ferment. It all goes out, nothing goes back in.


In a fixed volume the pressure is directly proportional to the temperature. So, reduce temperature and the pressure reduces. With a blow off tube or airlock the pressure before cold crash is atmospheric. Reduce the temperature and, provided the fermenter is sealed, you create a vacuum. Hence suck back of 500ml mineral water!


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## mofox1 (22/9/17)

Danscraftbeer said:


> I'm still confused as to how 500ml water gets sucked back into your brew?
> All being in the same temperature control I cant understand how it could happen.


Because it's not at a single temperature.

When you cold crash the beer, as in set the fridge temp to -1 or so, it will create a vacuum which will suck up the water.

I still use a dirty old plastic fermenter, and quite happy to bung a clamp over the blowoff tube once it's done. Yes, plastic has its advantages.

Edit: ah, just read you're a pressure ferment dude... As long as you have enough postive pressure at ferment temp to at least equal atmo at freezing, you're good. Not applicable for the OP tho.


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## Danscraftbeer (22/9/17)

Concur.
Its just that if you tune your process in the way that it only expels. Even cold chilling will never get to a vacuum. I'm a little confused here. Really 500ml sucked back?


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## fletcher (22/9/17)

Bribie G said:


> No, the title of this thread didn't accidentally miss out "babes" or anything so settle down chaps.



well shit. this comment ruined my witty remark >.<


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## mofox1 (22/9/17)

Danscraftbeer said:


> Concur.
> Its just that if you tune your process in the way that it only expels. Even cold chilling will never get to a vacuum. I'm a little confused here. Really 500ml sucked back?


Well, if you are not pressure fermenting, then **** yeah. You only chill after ferment is complete, and while there is some excess CO2 in solution, it's not enough to replace the volume that is lost due to cooling. Also note that the colder you get, the more soluble the CO2 is and less able to come out of solution.

So, If you have 10 - 20L of headspace, and about 50 to 100ml in your blow off tube, then the contraction due to temp is going to be a lot. Yes, 500ml a lot.

I'm sure there are calcs (ie ideal gas formula, PV = nRT) but I really can't be arsed with them. You cool stuff down, it gets cold. You cool a vessel with a headspace and it will implode if it's not strong enough to hold a vacuum.

As mentioned in a previous post, a phat assed blow off tube would help, as there is more volume in the tube... Although I'm guesstimating that it would need to be a couple inches dia to really be of use.


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## TidalPete (22/9/17)

Brewno Marz said:


> Is there a number 4? No cold crash, just keg and accept the great, but bit cloudy beer, you've made.



An excellent choice if you are fermenting a Wheatie,Whit, Saison or a similar beer.


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## Black n Tan (23/9/17)

With a conical I just connect up the CO2 and give it a few psi, turn off gas and crash chill. However not so easy with your set up. How about just replacing the blow-off water with fresh boiled water and add a pinch of metabisulfite. That will minimise the O2 pick up. Better than sucking in air.


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## Bribie G (23/9/17)

Been tying myself in knots over this one... I'll actually try plan A and just attach a bag to the end of the tube to fill with CO2 and see what happens, will post pix. I'm using the San Diego Super Yeast again, pitched Thursday so I'll be on the lookout Sunday pm.


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## hotmelt (23/9/17)

Why not take the poppet out of a carb cap,attach it to your blow off hose,then squeeze the air out of your bottle and screw on to carb cap.


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## Gelding (23/9/17)

I also had this problem. Actually its a good problem to have, because it means that your fermenter can hold pressure if needed (eg fermenting under pressure if thats what you want to try, but its another story).

I solved it two ways.

1) instead of a liquid receptacle, just cover the end of the blowoff tube with tin foil so nothing can crawl up there (even if it did, co2 would ensure limited progress) remembering that during active fermentation you have positive pressure so the flow direction is out. When you cool or crash, you will suck back a bit of air but noticed no deletirious effects on my beer. But sucking back air is batter than spring water (or starsan!)
2) if you are concerned about air and possible oxidation, the more anal way is to pressurise your fermenter with co2 before chilling. you could do this because your fermenter can hold pressure. after fermentation is complete and before you chill, blow into your fermenter around 15 to 20 psi of co2 and seal. You will need to modify your outlet to include a small valve to achieve this though.


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## Jack of all biers (23/9/17)

Bribie G said:


> Been tying myself in knots over this one... I'll actually try plan A and just attach a bag to the end of the tube to fill with CO2 and see what happens, will post pix. I'm using the San Diego Super Yeast again, pitched Thursday so I'll be on the lookout Sunday pm.



Bribie, I saw a post a few weeks back where someone did exactly that. The bag (medical plastic thingo) was connected between the blow off and the water/sanitizer solution. The bag fills with CO2 first, holds pressure and when the cold crash pressure drop occurs only the CO2 from the bag is sucked back stopping o2 and water getting back in.
Has to be able to hold pressure and be big enough to act as a gas reservoir for the change in volume.

Wish I could link you the thread, but on phone and can't remember what it was titled. As I said though it was only a few weeks back I saw the post.

EDIT- there was possibly a plastic valve on the bag to ensure water wasn't sucked back, but can't remember.

2nd EDIT - Ha. On my PC now and a quick search and here it is https://aussiehomebrewer.com/threads/preventing-cold-crash-suck-back-in-fermenters.96165/


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## Lyrebird_Cycles (23/9/17)

The easy solution is to make the tube longer. Assuming your ferment is at 15 - 20 oC, the suckback volume when cold crashing is at most about 15 % of your headspace volume*. Make sure your tube is long enough to accommodate more than this volume and you are gold.



* This assumes that the reduction in pressure though the equilibrium shift due to the increase in solubility of CO2 at the lower temperature is too slow to be important.


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## mofox1 (24/9/17)

Lyrebird_Cycles said:


> The easy solution is to make the tube longer. Assuming your ferment is at 15 - 20 oC, the suckback volume when cold crashing is at most about 15 % of your headspace volume*. Make sure your tube is long enough to accommodate more than this volume and you are gold.
> 
> 
> 
> * This assumes that the reduction in pressure though the equilibrium shift due to the increase in solubility of CO2 at the lower temperature is too slow to be important.


My math might be bad, but 1m of 10mm dia tubing is ballpark 100ml...

If I have 10L of headspace, that's 1.5L volume reduction. I'd need 15m for 15L headspace! Or much fatter tubing... ~30mm dia to get it in 2m.

Starting to think that having a CO2 suck back bag might not be a bad idea.


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## Black n Tan (24/9/17)

mofox1 said:


> My math might be bad, but 1m of 10mm dia tubing is ballpark 100ml...
> 
> If I have 10L of headspace, that's 1.5L volume reduction. I'd need 15m for 15L headspace! Or much fatter tubing... ~30mm dia to get it in 2m.
> 
> Starting to think that having a CO2 suck back bag might not be a bad idea.



Yer your maths is out 10-fold. 1 meter of 10mm ID tube will hold 785mL. So you need about 2 metres for 1.5L.

Edit: 1 meter is 78.5mL


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## mofox1 (24/9/17)

Black n Tan said:


> Yer your maths is out 10-fold. 1 meter of 10mm ID tube will hold 785mL. So you need about 2 metres for 1.5L.


http://www.handymath.com/cgi-bin/cylinder.cgi?submit=Entry reckons 78ml for 1m of 10mm dia tube.


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## Black n Tan (24/9/17)

mofox1 said:


> http://www.handymath.com/cgi-bin/cylinder.cgi?submit=Entry reckons 78ml for 1m of 10mm dia tube.



Right you are, my mistake.


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## Danscraftbeer (24/9/17)

I like the idea someone already mentioned to use a carb cap on the blow off bottle with dip tube to the bottom of the bottle. Have the cap loose when in active ferment is the same as what he has now. Ideally a 2 or 3lt bottle. You really dont need any water in it either since the bottle gets well and truly purged with co2. Near end of ferment, prior to cold crash tighten the carb cap so the bottle will become pressurized. That's instead of stuffing around and swapping to a co2 balloon bag etc. The bottle will collapse when it chills down.
Reason I pressure ferment is because of the bonus advantages of using your brews own produced co2 saving on bottled co2 and a fair bit of messing about as well.
$0.02


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## Lyrebird_Cycles (24/9/17)

mofox1 said:


> My math might be bad, but 1m of 10mm dia tubing is ballpark 100ml...
> 
> If I have 10L of headspace, that's 1.5L volume reduction. I'd need 15m for 15L headspace! Or much fatter tubing... ~30mm dia to get it in 2m.
> 
> Starting to think that having a CO2 suck back bag might not be a bad idea.



Yes that's more headspace and thinner tubing than I'd reckoned on. The bag is probably easier.


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## Bribie G (24/9/17)

With the brew bucket I use a very thin tube as it fits into the drilled plug that came with the BB. I'll measure the ID and do a quick pie arrh squared aitch calculation and see how much I'd need. If kept as a neat coil it shouldn't be unwieldy and not really expensive - LHBS and BCF sell a range of tubing.


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## Black Devil Dog (25/9/17)

I reckon something like this would be ideal. Available in different sizes up to 3 litres.
Pretty much plug and play. Nice little screw cap to purge/vent if need be.
Plenty of different types here.


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## DJ_L3ThAL (25/9/17)

What do commercial breweries do? They'd have large temp swings when say the glycol system kicks into gear that would multiply out to a decent volume of 'suck back'. I've seen a couple and from memory the internal diameter was no greater than 1 inch (25.4mm) and a FV height of 3m, which is is approx 1 litre of hose volume. 

How much volume change could a 2000L FV have? Even a 1 degree swing with no active ferment at the time would result in more than 1L volume change wouldn't it?


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## nosco (25/9/17)

I think I read on here some where that you can fit a 1/2" silicone hose straight in to the top of the BB lid which might help, I dont know how. Ive also seen people put a hose over the inside tube on a 3 piece air lock as a make shift hose adapter. The valve on my 20lt collapsible water container (that ive never used) has a 10mm OD on the outlet.

I have been swapping the blow off with an air lock after the main ferment is done but that introduces O2 of course. I think I might try this next time I use my BB. I have been using a blow off tube all the time now with my BB as I always get "blow off". I am probably over filling a bit. 

My only concern with the collapsible container would be cleaning it. It is clear though so it shouldnt be a problem.


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## Black Devil Dog (25/9/17)

Cleaning it shouldn't be a problem since it's only being used once the vigorous fermentation has subsided and it's just capturing the co2.
Another option would be to fill it with co2 from your bottle and only attach it to your fermenter when you're ready to chill.
I've ordered a couple, keen to try it.


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## Lyrebird_Cycles (25/9/17)

DJ_L3ThAL said:


> What do commercial breweries do? They'd have large temp swings when say the glycol system kicks into gear that would multiply out to a decent volume of 'suck back'. I've seen a couple and from memory the internal diameter was no greater than 1 inch (25.4mm) and a FV height of 3m, which is is approx 1 litre of hose volume.
> 
> How much volume change could a 2000L FV have? Even a 1 degree swing with no active ferment at the time would result in more than 1L volume change wouldn't it?



Commercial breweries have pressure regulators and vacuum breaker valves on the tanks so suck back doesn't occur. You'd need -30kPa of vacuum to suck back on a 3 metre line.


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## DJ_L3ThAL (25/9/17)

Lyrebird_Cycles said:


> Commercial breweries have pressure regulators and vacuum breaker valves on the tanks so suck back doesn't occur. You'd need -30kPa of vacuum to suck back on a 3 metre line.



Rightio! Do the vacuum breaker valves just let air in? (Albeit a small amount proportional to the headspace).

Back on HB scale, the water bladder or simple spring water bottle are good ideas. Anyone know of a PET bottle cap that has a 9mm or 12mm hose tail/barb on the outside as well as inside? Or could just use a carbonation cap and a quick disconnect. Think I even have the fittings for the latter and an adaptor for my Chronicals with John Guest push fitting so I can supply CO2 when kegging/bottle to avoid air ingress.


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## Matplat (26/9/17)

What about having an intermediate vessel to increase the volume of your blowoff line? Then the water would just fall into the empty intermediate vessel, and you'd just have to be sure you have enough water in the air lock bottle so that only water gets drawn through, not air.

A bit more cumbersome, but simpler I think?


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## earle (26/9/17)

Simpler is better for a blow off arrangement I think. It's one thing to think about gas being blown off but once you add some krausen into the mix I reckon some of the suggestions could get a blockage.

What about running the blowoff tube into a 3 or 4L pet bottle with say 500ml liquid in the bottom. Drill a hole in the cap of the blow off bottle just large enough so that your blow off tubing can form a seal (maybe a bit of keg lube would help get a good seal or add a grommet if this doesn't work). During ferment have the end of the blowoff tube in the liquid and the lid of the bottle slightly loosened to release excess pressure, but still retain co2. When you cold crash, withdraw the tube from the bottle but not completely so the end is just below the lid. Tighten the lid so that air is not drawn into the bottle. As your fermenter cools and creates a vacuum, it should draw in co2 from the blow off bottle but not liquid, and the bottle can collapse in


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## Lyrebird_Cycles (26/9/17)

DJ_L3ThAL said:


> Rightio! Do the vacuum breaker valves just let air in?



The vacuum breakers would let air in if they actuated but I've never seen one actuate from normal temperature changes in the beer, they're designed to protect against cloth eared gits rinsing hot tanks with cold water and such like.


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## Bribie G (26/9/17)

I caught the brew at the end of the fermentation and fitted a simple plastic bag, tightly squeezed into the hose with that green garden tie wire and squashed flat, it hasn't blown up like a balloon but there's easily a litre in there - I'll drop the whole thing to -1 probably starting tomorrow.


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## good4whatAlesU (26/9/17)

I recall doing CPR (first aid training) and there were a number of 'one way valve" contraptions allowing air to move only one way.

https://www.cpr-savers.com/Ambu-One-Way-Valve-with-Filter-for-Res-Cue-CPR-Mask_p_7789.html

http://www.aplhealthcare.com.au/adv...MI0_XkqeLB1gIVhwYqCh2hjwHwEAQYASABEgIVx_D_BwE

edit: also gadgets for bleeding brake lines (one way liquid valves): https://www.catch.com.au/product/mo...MI9fSv6fHB1gIVRxdoCh3VeAF7EAQYASABEgL-qPD_BwE


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## nosco (26/9/17)

I like the look of this one for a co2 bag

http://www.ebay.com.au/itm/5L-Colla...e=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649


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## malt junkie (26/9/17)

Make an air lock chamber/jar, two hoses through the lid one just long enough to go through the lid the other 2/3 to the bottom of the jar, short goes the the ferm, long goes to container of liquid. 
Job done.


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## nosco (26/9/17)

I did think about that at first. I wonder what happens to the 02 that is in the chamber to start with? I guess it depend on the size of the chamber. When you CC wouldnt it still be sucking in air?


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## rossbaker (27/9/17)

+1 for the carbonation cap idea with a 2-3l pet bottle. You could manually purge it with co2 to be certain no O2 gets sucked back in. I'd be interested to see how much the pet bottle implodes.


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## unwrittenlaw (27/9/17)

You could keep topping up the PET bottle daily


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## RobB (27/9/17)

Depending on your starting head space, this could be a plug and play solution.


It's an inline filter housing with push fittings, about $30 on ebay. At 10"x2.5", this would add about 750mL to the volume of your blowoff hose. This should be enough to allow you to start with 11L of headspace and chill from 20C to 0C.

If you start with a larger head space or are chilling from a higher starting point, you will need more volume than this housing provides, but I still think that adding a large inline chamber along the blowoff is the simplest way to go. A short length of 100mm PVC pipe with end caps could be a good starting point for a ghetto solution.


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## Bribie G (2/10/17)

I think my quick and dirty method has worked pretty well. When I took my 2 deg C brewbucket out for kegging just now, there was still a fair bit of "puff" left in the blue bag despite the cold crash.





When I started transferring, the bag got sucked in quite tightly and runoff slowed so obviously airtight enough for purposes. My next move will be to find a more sophisticated bag, and maybe a hose clamp.


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## Black Devil Dog (2/10/17)

I thought you'd connect your transfer hose to a beer quick disconnect rather than have it run inside the keg Bribie. 
Gas quick disconnect to let the air out as the keg fills.


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## Bribie G (2/10/17)

The keg is initially filled with 100% CO2 and as the liquid level rises the CO2 is expelled, pushing out any stray oxygen that is trying to get in from the other direction, damn its little shoes and breeches.
At the end of the fill, the headspace is immediately flushed with CO2.


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## Black Devil Dog (2/10/17)

Nice ball valve. I've been meaning to upgrade mine, but haven't yet. Where'd you pick that up from?


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## Bribie G (2/10/17)

From a mate who had access to erm erm erm some where he worked. 
sorry can't be more specific


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## nosco (2/10/17)

Does it have the size written on the side Bribey? Id love to replace the original. Its a bit shit init.

Are you still using the pickup tube with it?


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## Bribie G (3/10/17)

It's a STM 3/8" with a couple of codes stamped on the sides.

316. 1A6

1000 WOG

Obviously assembled by a Greek dude.

Bits and bobs from Reece etc but youll need to play with rubber grommets and o rings. A forum member made me up a bulkhead fitting that the valve screws into but you might want to check how other BB users have adapted Ball valves.

I never found the racking arm much use and it can't be used with the ball valve. I get a good keg full per brew, a couple of glasses to test out of primary and about a litre of yeast in the cone that I simply run out of the tap, so quite happy.


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## nosco (20/10/17)

It was a good idea at the time but i think i might pop the bung before it inflates much more. I put some dry hops in down the bung hole to try and minimise air as much as i can. That kicked up a heaps of CO2 which hopefully flushed out any air.

My other stainless fermemnter has a weld less keg post on it so it should work better on there.
Im hoping to catch enough CO2 for a CC and for the transfer to keg.


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## nosco (20/10/17)

Seems to be working with no leaks. It inflated to this size in about 30 but it hasnt changed an hour later.


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## nosco (20/10/17)

Pic


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## Black Devil Dog (20/10/17)

nosco said:


> It was a good idea at the time but i think i might pop the bung before it inflates much more. I put some dry hops in down the bung hole to try and minimise air as much as i can. That kicked up a heaps of CO2 which hopefully flushed out any air.
> 
> My other stainless fermemnter has a weld less keg post on it so it should work better on there.
> Im hoping to catch enough CO2 for a CC and for the transfer to keg.View attachment 109044



There's a bit going on in that photo nosco, so much to observe. 
Are you using a party balloon for your 'suck back sack'?
Your fridge has got me intrigued, have you extended a bar fridge or something similar?
That spaghetti would go great in a bolognaise.
Love the wheels on the fermenter.


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## nosco (20/10/17)

Yep party balloon. I got the jumbo one in case but maybe didnt need to. $2 for 5.

The bar fridge is extended out to fit 2 fermenters. It can hold ale temps with 2 fermenters no probs in summer but CCing isnt possible. I can do a lager in winter by blocking of the fron half with some insulation board. I have a bigger fridge as well now so no need. I got the idea off youtube.

The castors are from bunnings. 25mm i think. They didnt quite fit so i had to plug em in with silicone tape. I love silicone tape. Its on the balloon as well. They have been washed a few times and havnt shown signs of rust yet.

The spagetti is a reptile heater.


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## nosco (20/10/17)

Ive had to de-gas it twice. Its an over hopped I/IPA kinda thing. 5 days old. I havnt taken a sample yet but maybe its the dry hops nocking the co2 out of the krausen. Or maybe i was a bit early with the balloon [emoji1]


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## Danscraftbeer (21/10/17)

BANG!


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## nosco (21/10/17)

Lucky i got the jumbo one.


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## Moog (23/10/17)

here's an idea........., do you think you could fit a carrier bag over the mouth of a plastic fermenter, the same way people use glad wrap, then it can inflate right up and vent by escaping past the rubber ring seal , and suck back down during cold crash.
If it sucked back too much and touched the beer, could it cause an infection?
If the touching the beer is seen as a problem, you could rest a Perspex disc, bigger than the mouth opening (maybe add a couple of small holes in it), on top before the bag goes on, then the carrier bag can only deflate until it touches the disc.
Could this work?


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## Kev888 (24/10/17)

I'm not into LoDo myself, but do use CO2 pressure to push the beer out (because the FV valve is lower than the keg); as a side effect it also stops oxygen being drawn in during the transfer. About 1 or 2 psi is applied using a primary/secondary regulator combo, and there is a ~3psi safety valve fitted to the FV. The FV needs to be able to safely take that, but it isn't very much really.

In theory that could also work for when crash cooling, but the pressures are so small (and the time period longer) that I'm not sure I would be confident in the regulator not creeping slightly and losing all my gas. A cask breather (or aspirator) would seem a better idea for that stage (I believe people have made these by reversing a propane regulator or similar).

The balloons & bags are a good idea, but if you are serious about LoDo then something oxygen-impermeable could be needed (CO2 pressure does not prevent the ingress of oxygen, being a dissimilar gas). TBH in a homebrew scenario I personally just use the cotton-wool filter when chilling and let the yeast deal with any oxygen, as I don't filter them all out or pasteurise the beer, but I realise people have different viewpoints on this.


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## nosco (24/10/17)

Moog it might depend on how much room you have in your fermenting fridge/area.

Kev i can do that with one fridge but the other is too gar away from my co2 bottle. 

As i turns out balloons are not air impermeable. The balloon went flat after i had been carefully watching it over the weekend. They are also very atttactive to 2 year olds who like to yank the hose out of the plug and run off with it. I have a colapsable water container on order but it taking its time getting here.


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## Black Devil Dog (29/11/17)

Connected my new 'suck back sacks' last night and they're already tight.
I snipped the valve off the end and the tube fits snugly into the silicone plug that comes with the Brewbucket.
These are are a couple of lagers that are d-resting.


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## DJ_L3ThAL (29/11/17)

What fan is that mate? Looks perfect to push around ferment fridge air! Is it 240V or otherwise?

Also I may have missed it but can’t find link to the blow off suck back sacks (LOL)?

Can’t wait to tell the wife I just bought some blow off sick back sacks or BOSBS’ [emoji23][emoji23][emoji23][emoji23][emoji23]


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## Black Devil Dog (29/11/17)

The fan is from Jaycar. Katabat is the brand, they're great, they come with a really short USB lead though, so I bought a longer one to run into my fridge.

Here's the link to the suck back sacks.


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## nosco (29/11/17)

The baloons worked ok but couldnt hold the co2 for more than a day or 2. The collapsable container i used was a bit the same. It jas a valve on it so maybe some gas was escaping from there. The process seemed to work well enough but i cant say if it improved beer or not. Maybe that says more about the brewer [emoji16]. The only down side maybe is that there wasnt enough co2 in the container to last the whole keg transfer. Maybe one advantage of the baloon is that you can fill it alot but its maybe not worth the trouble.


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## S.E (29/11/17)

nosco said:


> The baloons worked ok but couldnt hold the co2 for more than a day or 2. The collapsable container i used was a bit the same.



Some collapsable containers are better than others. I have a couple from eBay that stay up and others from Aldi that will only stay up for a few days to a week.


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## mofox1 (30/11/17)

Just found these at kmart - $8 a pop, with tap lid. Could be a goer... I'll pick one up tomorrow - just in time too, if I want to start cold crashing early next week.


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## DJ_L3ThAL (30/11/17)

Are the walls collapsible mate? If not I don’t think that’d work from the vacuum being created etc


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## mofox1 (30/11/17)

Yep, they come folded up in a little square.


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## mofox1 (3/12/17)

Here we are, Kmart collapsible containers in use. Tap end fits into the end of the blow off tube.

Seem fill alright, we be interesting to see how the CC goes.


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## Dylo (13/1/18)

This is a pretty cool solution I saw. Don’t know how much volume is needed for everyone’s setup, but you could use bigger jars.


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## CJW (13/1/18)

Dylo said:


> Don’t know how much volume is needed for everyone’s setup, but you could use bigger jars.


Probably about the volume of contraction of the beer and CO2 in the ferrmenter when it cools from fermenting to cold crashing temperatures.


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## GalBrew (14/1/18)

mofox1 said:


> Here we are, Kmart collapsible containers in use. Tap end fits into the end of the blow off tube.
> 
> Seem fill alright, we be interesting to see how the CC goes.
> 
> ...



Any update on how cold crashing went with this setup? How much did the bag inflate? I admire the simplicity of this setup very much.


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## mofox1 (14/1/18)

GalBrew said:


> Any update on how cold crashing went with this setup? How much did the bag inflate? I admire the simplicity of this setup very much.


Really great - I've done it a few times now. The initial suck back during rapid cool doesn't deflate the bag too much, but interestingly, over the next few days it will continue to deflate until the bag pulled back in to a compact shape. Perhaps the beer absorbs a few litres of CO2 when the temp is dropped?


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## FatDrew (14/1/18)

I employed the Kmart collapsible water carrier on a recent batch.

Batch size was 23L in 30L HDPE fermenter. I’d estimate that the bag can be fully inflated 10L volume with approximately .003 to .004 for this batch size, so important not to attach it too early in the ferment, as you risk pressurising the system too much or creating a leak or blowout somewhere.

Something I found useful: if the bag fills before the end of the fermentation, you can close the valve, loosen the lid of the bag slightly and express some CO2, then close lid and reopen valve. 

Also I found it sealed well enough to fill w CO2 from the ferment, close valve, disconnect from fermenter and save for use in cold crash later. Of course, I can’t be sure that no air passed into the bag while stored this way, though the size and pressure appeared constant across the ~3 days stored closed and disconnected from the fermenter.

Similar results observed to those mentioned above in terms of the volume of gas taken back into the fermenter during cold crash. I attached the bag at about half full (3-6L estimated) at start of cc and over about 3 days at 1deg the entirety of this was drawn into the fermenter.


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## Patrick_BCB (14/1/18)

I use a freezer bag threaded thru the silicon bung. I fill from a tank though, might try to harvest from the ferment next brew.
I do this for crash chilling, and when transferring to the keg - which takes about 3 bags full of gas to complete. Same SS brewbucket too,

https://aussiehomebrewer.com/threads/crash-chill-co2-method.95402/


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## Damranger (14/1/18)

Deleted


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