Issue with fermenter, can I add top-off water after fermentation?

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nasmeyer

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I have brewed 8 batches of extract ale with my Mini-Brew 6.5 conical. This conical has many advantages, but few disadvantages as well. My most recent concern is with the airlock filling with krausen during fermentation. My photo shows that my plug for my airlock sits between the 6 and 6 1/8 gallon mark, and when I ferment 5.25 gallons, and have a vigorous fermentation, my airlock will plug up. I could just ferment 5 gallons, but after dumping the yeast, and taking a couple of gravity readings, I might only have 4.5 gallons left at bottling time.

top_of_conical.jpg


What I would like to do is just boil and ferment a 4 gallon batch, and add distilled H2O after active fermentation to get back to 5-5 1/2 gallons, but was wondering what kind of negative impact of issues I might run into.

Would I need to boil the water to expel any oxygen? Would I mess up my hop utilization by boiling 4 gallons instead of 5? I am guessing I would need to re-calculate my starter size due to a more concentrated wort gravity? At what point would I add my H2O, after the krausen has subsided, or might I just boil the priming sugar in the amount of H2O I need to top off? What other issues might I have?

Yes I could use a different fermenter, buy a stainless conical, or build a “stack tube” for the airlock plug, but this is the fermenter I have to use for now.

Another potential disadvantage I have found is that it appears that up to 3/8 of a gallon of oxygen might be trapped from the bottom of the airlock plug, to the top of the conical where the plastic lid is secured. CO2 should still give me a layer on top of the beer but I am not sure. I am considering adapting an airlock attached to the lid itself, but since it is flexible it won’t be easy. I was thinking of finding a 6" diameter sleeve (stainless? glass? sched 80 pvc?) and hose clamp it to the top of the conical, then attach my airlock to the top of that. Too bad I have this issue, it is a great product otherwise.
 
This doesn't answer your question, but is there any reason you cannot just use a blowoff tube? It would be a much simplier solution, unless I am missing something.
 
It seems that you have a difficult situation. Keep in mind that I have absolutely no experience with your issue, but I do like problem solving. If you add H2O to your beer after fermentation I would make sure to boil it to drive off any impurities as well as O2 that might be in solution. You would have to calculate the amount of water you are adding later into the total gravity and bittering that you are using. Also, you might be able to make a hop tea with the additional water to add some bittering. With gravity units, you would likely be stuck with the gravity of the original wort.

My best guess is that the easiest solution would be to plug your current airlock valve and modify your lid to accept the airlock. As an interim measure you can do as cshamilton suggests and use a tube.

Good luck with this project!
 
This doesn't answer your question, but is there any reason you cannot just use a blowoff tube? It would be a much simplier solution, unless I am missing something.
Im not sure how much I will lose through a blow-off tube. I would rather keep everything in my fermenter if I could. But it is an idea I have considered. This also wouldn't be a solution for my possible trapped O2 in the lid area.
 
You could just drill a hole the same size as the airlock hole in the vessel into the lid, move your airlock there, and get a solid plug for the airlock hole.
I don't recommend adding water to any beer after sparging. :)
 
You could just drill a hole the same size as the airlock hole in the vessel into the lid, move your airlock there, and get a solid plug for the airlock hole.
I don't recommend adding water to any beer after sparging. :)



The lid is very thin, soft, and flimsy. It is like this so it seals tight when in use. Drilling wouldn't be necessary, but cutting a hole and placing an airlock into it would just fall from side to side because there would be no support. I am thinking maybe using a sched 80 6" pvc cap, hose clamped to the top of the conical with an airlock hole drilled in the top?
 
Check out "home brewer TV" on youtube he has a "monster fermentation" episode that will solve your problem. All it is, is a giant air lock that drains beer collected back into your conical.
 
nasmeyer said:
The lid is very thin, soft, and flimsy. It is like this so it seals tight when in use. Drilling wouldn't be necessary, but cutting a hole and placing an airlock into it would just fall from side to side because there would be no support. I am thinking maybe using a sched 80 6" pvc cap, hose clamped to the top of the conical with an airlock hole drilled in the top?

You wont be able to use a hose clamp on a pvc cap....it will not work, since the cap is rather ridgid. I would suggest if anything, try to visit a plumbing supply house (not home depot) and purchase a gauge glass for a steam boiler, ask them to cut it to desired length, plug your existing air lock hole, and drill a new one to accomodate the gauge glass and adapt your air lock to the other end.

I seriously doubt that you have any trapped O2 under the lid, but just to be safe, once active fermentation kicks in, remove the lid for a handful of seconds and then put it back on. atmospheric pressure (the pressure of the air that surrounds us every day) is 14.7 psi. The pressure inside a fermenter will typically peak around 38 psi. I know this because I am the fool who actually drilled a hole in my bucket lid and mounted an actual pressure gauge. The differential pressure will not allow anything to enter the fermenter, but will definitely expel any oxygen. The thing is, though, that the pressure inside your fermenter will usually expel O2 anyway.

Good luck.
 
this is the second time I've posted this in as many days, and yet I haven't tried it myself...
still, this looks like a possible solution to your volume issue:

http://***********/stories/projects...self/354-build-a-burton-union-system-projects

On the trapped O2 lid deal, I don't know - you could loosen the lid once fermentation begins so that the O2 is purged by the CO2 being created - then tighten it back down.
 
I know this may seem too simple, but why not plug the airlock port and replace the lid with a piece of aluminum foil?
 
Just use Fermcap or any other anti-foam. You can fill it right to the top and no problem. No affect on final foam retention either. Great product. Cheap aand available through many homebrew stores (Nothernebrewer, Midwest supplies, Williams, Rebelbrewer, etc.). Just look it up on this site for more info. I've used it for years. Love it.
 
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