Efficiency too high?

So, indeed, only thing you haven't changed is the co2 supplier, co2 tank and the lines.

I think you've narrowed it down. Fingers crossed. Good luck!

The welding shop I go to does a tank exchange.

Hopefully work will give me enough of a break for me to able to go out today and buy new QD's and gas lines.

I was also going to get my tank filled at another location, but then I started thinking I'm going to have them fill a CO2 tank that I've had problems with. Is it just going to prolong my issues and make troubleshooting more difficult? What are my alternatives? Buy a brand new CO2 tank? That's a lot of $$$ that I'd rather not spend right now.

LovesIPA said:

[...] What are my alternatives? Buy a brand new CO2 tank? That's a lot of $$$ that I'd rather not spend right now.

Click to expand...

Yeah well, say a 5 gal batch costs you 25$ (plus the time involved in making it) and all the ones you dumped, 80-100$ seems to be a bargain...

LovesIPA said:

I looked for a pH meter on Amazon, and for $13 I certainly don't have any excuse not to have one. Should be here tomorrow.

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How did the ph meter work out for you, I think I have seen the one you purchased and I don't think it is well suited for brewing. You want to look for one with accuracy of .01. Also did you get solution to calibrate?

It seems to work pretty well but it's only accurate to .1 as you noted. It did come with calibrating solution.

I'm not sure mash pH is the cause of the problem. I think that part of my process needs improvement, but I'm not convinced it's causing the really strong off-flavor and aroma I'm getting.

LovesIPA said:

It seems to work pretty well but it's only accurate to .1 as you noted. It did come with calibrating solution.

I'm not sure mash pH is the cause of the problem. I think that part of my process needs improvement, but I'm not convinced it's causing the really strong off-flavor and aroma I'm getting.

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Exactly, plus your bottled batch was fine, it would have suffered from the same water chemistry too.

I think you narrowed it down to the gas system.

LovesIPA said:

The welding shop I go to does a tank exchange.

Hopefully work will give me enough of a break for me to able to go out today and buy new QD's and gas lines.

I was also going to get my tank filled at another location, but then I started thinking I'm going to have them fill a CO2 tank that I've had problems with. Is it just going to prolong my issues and make troubleshooting more difficult? What are my alternatives? Buy a brand new CO2 tank? That's a lot of $$$ that I'd rather not spend right now.

Click to expand...

You know you can/should take those disconnects apart and soak in Starsan. Or "boil" in PBW to really kill things.

If it is the tank, swap it out at a different, perhaps more trusted location.

BTW Scotty sells tanks for a good price.

Busy day yesterday. I went to the LHBS and bought new gas side QD's and lines. I also stopped at a different place for my CO2. This is a place that specializes in fire extinguishers. I talked with them a little bit in the front office and for $22, then will remove the valve from the tank, pressure wash it with 180* water, and replace the o-ring. Please do it, I said. The tech said that when he removed the valve, he could definitely smell something foul coming from the tank. He ran it through the washer (I forget what he called the thing) twice before he re-filled with food grade CO2. It ended up costing me about $45 for the whole thing. I have another cylinder that's going to get the same treatment pretty soon. The best part is that they refill while you wait instead of exchanging tanks. So I will be keeping this tank for a long time.

After I got home, I replaced all the QD's and lines and then kegged two beers. I should know in a day or two whether I've solved the problem or not.

Thats good new man. I think.

I just goto airgas for my co2, I have no affinity to my co2 tank and just have it exchanged.

LovesIPA said:

Busy day yesterday. I went to the LHBS and bought new gas side QD's and lines. I also stopped at a different place for my CO2. This is a place that specializes in fire extinguishers. I talked with them a little bit in the front office and for $22, then will remove the valve from the tank, pressure wash it with 180* water, and replace the o-ring. Please do it, I said. The tech said that when he removed the valve, he could definitely smell something foul coming from the tank. He ran it through the washer (I forget what he called the thing) twice before he re-filled with food grade CO2. It ended up costing me about $45 for the whole thing. I have another cylinder that's going to get the same treatment pretty soon. The best part is that they refill while you wait instead of exchanging tanks. So I will be keeping this tank for a long time.

After I got home, I replaced all the QD's and lines and then kegged two beers. I should know in a day or two whether I've solved the problem or not.

Click to expand...

:fingers crossed:

Both newly kegged beers have the off-flavor now.

I should add that I soaked the manifold in bleach for about 15 minutes too. I rinsed it out thoroughly, blew it out with CO2, then rinsed thoroughly and blew it out again. I noticed that two of the valves didn't flow as well as the third. After blowing it out with CO2 the first time, one of them opened up and started flowing as well as the other one. I couldn't get the third one to do the same. It just isn't getting the same amount of flow as the other two do. Nothing came out while I was rinsing it or blowing it out.

To be fair, these valves seem to be pretty cheaply made.

I did have a backflow once. I over-filled a keg past the "in" dip tube and of course the tank emptied a day or two later. I had beer all the way in the lines BUT both the manifold and regulator, and now the lines and QD's, have all been replaced since then.

If I ever have the ambition to brew another batch again, I'll carbonate it directly from the regulator, bypassing the manifold.

This whole ordeal just seems so ridiculous at this point. If it didn't want to make me cry so much, I would laugh about it.

You sure you're not mistaking carbonic bite as an off flavor?

BTW, did you edit that last post? I got something entirely different in my mail box.

IslandLizard said:

You sure you're not mistaking carbonic bite as an off flavor?

Click to expand...

Does carbonic bite completely erase hop aroma and flavor?

BTW, did you edit that last post? I got something entirely different in my mail box.

Click to expand...

Yes I did.

Carbonic bite definitely erases hop aroma and flavor. I had carbonic acid bite in a milk stout and brown ale and it completely erased the flavor and aroma of both. I believe the carbonic acid was caused when my cold CO2 tank ran out (I keep it inside the kegerator) and I hooked up a warm CO2 tank to the kegs. For some reason this resulted in carbonic acid in both beers. They didn't really seem too over-carbonated, but the flavor and aroma were gone.

To fix them I left both kegs out at room temperature for a couple weeks and I bled off the pressure each day until there was almost zero pressure left. Then I put both kegs in the kegerator to chill for a day and then hooked them back up to the same CO2 tank (which was cold now) that had caused the problem. After a couple weeks they were perfectly carbonated and tasted great.

So it turns out the CO2 wasn't bad, but switching from cold to warm CO2 gas may have caused the problem. Hopefully this will help out with your situation.

My CO2 tank stays in the keezer. It doesn't seem to matter if I use a tank that's been in there for a week or a brand new tank that's closer to room temperature.

That's interesting though. How do you normally carbonate beers now?

I'm skeptical it's the carbonation process, because I carbonate just like a lot of people do. I set it to 30 PSI for 24 hours, then dial it back to 10 PSI for a couple of days. After 3-4 days I get a perfectly carbonated beer. If this process causes carbonic bite, then why are so many people doing it this way? And how are they doing it and getting beer that tastes good?

There was something hanging out in the back of my mind about the manifold that I couldn't quite remember. This morning while I was re-reading this thread, I remembered what it was.

Remember that I had the backflow sometime last year. I switched the manifold out because I had taken it apart for some reason - maybe to clean it? - and galled the threads on one of the shutoff valves. Then I bought another manifold to replace it, but the shutoff valves on that one were too large for my gas tubing.

So I removed enough of the threads on the damaged valve and swapped the valves from the old manifold to the new one and then completely forgot that I'd done so until this morning.

Could something be living up in those old shutoff valves that's causing this? A bit of mold perhaps?

I ordered three replacement shutoff valves with 1/4" barbs on them so we'll see.

Of course now I have to brew yet another batch of beer to test this out.

LovesIPA said:

My CO2 tank stays in the keezer. It doesn't seem to matter if I use a tank that's been in there for a week or a brand new tank that's closer to room temperature.

That's interesting though. How do you normally carbonate beers now?

I'm skeptical it's the carbonation process, because I carbonate just like a lot of people do. I set it to 30 PSI for 24 hours, then dial it back to 10 PSI for a couple of days. After 3-4 days I get a perfectly carbonated beer. If this process causes carbonic bite, then why are so many people doing it this way? And how are they doing it and getting beer that tastes good?

Click to expand...

I carbonate using the set and forget method. I set the regulator to 10-14 psi depending on the beer and let it sit for 2 weeks.

There is a higher chance of carbonic acid being introduced using the method you describe. Like you said a lot of people use this method and it does work, but the probability of carbonic acid bite being introduced is higher when compared to the set and forget method.

Try carbonating your next beer using the set and forget method and see if that makes a difference. You'll have to wait a couple extra weeks but it may be worth it to eliminate one more possible cause.

But there are PLENTY of homebrewers who do the burst carb method. And if it created a problem this serious, there would be warnings all over saying, "Don't carb your beer like this!" Instead, I see a lot of "I do it that way too" with a good mix of those who set and forget as well.

Am I being unreasonable in assuming that if this method were the cause of serious off-flavor problems there would be at least one person out there saying, "Don't do it that way"?

LovesIPA said:

But there are PLENTY of homebrewers who do the burst carb method. And if it created a problem this serious, there would be warnings all over saying, "Don't carb your beer like this!" Instead, I see a lot of "I do it that way too" with a good mix of those who set and forget as well.

Am I being unreasonable in assuming that if this method were the cause of serious off-flavor problems there would be at least one person out there saying, "Don't do it that way"?

Click to expand...

There are definitely people out there who recommend to set it and forget it over force carbing. It may work for most people but may not with your equipment and procedures. What temp range does your beer fridge run at? Also, consider that your pressure gauge could be out of calibration which could result in you mistakenly over carbing. I just over carbed a beer on accident and couldnt tell it was over carbed by pouring it. It just tasted bad. It showed up from one day to the next much like you describe. It might not be your problem but it is worth consideration.

I will try the set & forget method next time. My keezer is set to about 41 degrees.

What did your over-carbed beer taste like?

Bitter in a weird way i guess. It overpowered hop character for sure. Now that i know what it tastes like i realize its not the first time i have overcarbed. Pour a pint and whisk away the co2 as it warms. Easy test..

I'm sorry if this has been mentioned before but, have you tried really simplifying things? Maybe doing a BIAB, using only 1 vessel then bottle condition. If it works out add 1 thing back at a time to narrow it down.

LovesIPA said:

There was something hanging out in the back of my mind about the manifold that I couldn't quite remember. This morning while I was re-reading this thread, I remembered what it was.

Remember that I had the backflow sometime last year. I switched the manifold out because I had taken it apart for some reason - maybe to clean it? - and galled the threads on one of the shutoff valves. Then I bought another manifold to replace it, but the shutoff valves on that one were too large for my gas tubing.

So I removed enough of the threads on the damaged valve and swapped the valves from the old manifold to the new one and then completely forgot that I'd done so until this morning.

Could something be living up in those old shutoff valves that's causing this? A bit of mold perhaps?

I ordered three replacement shutoff valves with 1/4" barbs on them so we'll see.

Of course now I have to brew yet another batch of beer to test this out.

Click to expand...

Just don't mix new with old unless the old is made like new. You're trying a process of elimination. The manifold can be boiled, or even autoclaved in a large pressure cooker, with PBW, washing soda, or even an acid (makes it very shiny). Your oven is another way to kill whatever is in there, like I do with my plate chiller. 2-3 hours at 350-400. Goes well with pizza.

It's conceivable some bug is living a good live in that manifold or elsewhere, while giving you nightmares.

Maybe time to clean those regulators too, and what not.
Your gas supplier told you the bottle smelled weird. That's a valuable pointer, and I remember saying something about your CO2 a few months ago.

Again it doesn't seem to be your brewing, as your bottled batch was good. You should bottle a few (6-12) along with kegging to have a control group.

Having read through some of the newer posts may I suggest just replacing your co2 bottle? It looks like you have pretty much replaced everything else except the kegs which I really don't think is causing you the problem reading about your sanitization ritual.

It wouldn't cost you to much, as many places just do replacement outright for the cost of the co2 anyway.

The only thing beyond that is the regulator.

If you were having success with your quick carb method at first, and the problem developed over time then I don't know if it would matter which carb method you use. I personally have never tried the quick carb method. I just set my regulator a little high, maybe 14 or 15 psi for a week, then down to serving pressure. No problems yet for me.

Once again. Good luck dude. I hate to recommend replacement, but with the co2 canister it shouldn't cost you more than just buying the air outright anyway. I have a 5lb cylinder and it costs me about 18 bucks to replace.

Just thought about this.
An infection would take some time to develop, definitely in an alcoholic environment, like beer. So if a persistent bug lives in your kegging/dispensing system, you wouldn't notice it right away, it would be gradual, increasing over time, particularly when it's cold stored in your keezer.

So when you discover a keg has lost its appeal, how does that beer taste 2 weeks after that? 4 weeks? I hope you have not been dumping it right away. Maybe you're just very sensitive to carbonic acid.

I know when I force carb a keg, that beer does not taste right. But it gets better during the following 2 weeks. Some beers take a month or longer. And this is after a liberal fermentation/conditioning period. I typically leave it on the yeast for 3-4 weeks before kegging.

It definitely would be good to get feedback from a few experienced tasters. Is there a homebrew club in your area? Other home brewers? Or a pro brewer? How about your LHBS?

Facinerous said:

Having read through some of the newer posts may I suggest just replacing your co2 bottle? It looks like you have pretty much replaced everything else except the kegs which I really don't think is causing you the problem reading about your sanitization ritual.

Click to expand...

See this post.

If you were having success with your quick carb method at first, and the problem developed over time then I don't know if it would matter which carb method you use. I personally have never tried the quick carb method. I just set my regulator a little high, maybe 14 or 15 psi for a week, then down to serving pressure. No problems yet for me.

Click to expand...

That's a really good point. Back when I used to be able to brew some pretty excellent beers, I would use the same carb method I do now. I think the first one I kegged I shook the crap out of it and it was fine.

IslandLizard said:

Just thought about this.
An infection would take some time to develop, definitely in an alcoholic environment, like beer. So if a persistent bug lives in your kegging/dispensing system, you wouldn't notice it right away, it would be gradual, increasing over time, particularly when it's cold stored in your keezer.

Click to expand...

I agree. This came up in the other thread as well and it makes sense.

So when you discover a keg has lost its appeal, how does that beer taste 2 weeks after that? 4 weeks? I hope you have not been dumping it right away. Maybe you're just very sensitive to carbonic acid.

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No, I'm not dumping them right away. After some time, the off-flavor lessens quite a bit. I brewed a Bell's two hearted clone a few months ago and after a couple days in the keg it was terrible. I took it out and let it sit at room temp for a couple of weeks and it went flat from a leaky poppet. When I hooked it back up, it wasn't terrible. There was no hop aroma or flavor, but the off-flavor had faded quite a bit. It tasted like a pale ale with no finishing or dry hops at all.

It definitely would be good to get feedback from a few experienced tasters. Is there a homebrew club in your area? Other home brewers? Or a pro brewer? How about your LHBS?

Click to expand...

I've taken it to LHBS's and pro brewers before but the flavor fades quite a bit by the time I get it to them. It's definitely strongest right out of the tap, and right after I tap the keg. The hop aroma and flavor never comes back, no matter how long I wait.

Most people that have tasted it don't pick up on it because it fades. I can still taste it at the LHBS because I know what it's like when it's strong and I can still taste it, but other people claim they don't notice it.

I have e-mailed a BJCP certified judge who lives in the area, and another person on facebook who runs a homebrew "school". Neither one responded.

Time for an update I guess.

Pretty much nothing I've tried has panned out. However, I read one of those "stump the expert" columns in BYO magazine and someone wrote in and described the problem I was having pretty much exactly. He described the beer as tasting like rose-water, which I can definitely agree with. The expert seemed to think the problem was oxidation. It seems that some sources of CO2 are not 100% pure. Even as much as 0.05% oxygen in the CO2 cylinder is enough to cause oxidation flavors. Also, just purging the keg a couple of times with CO2 like I've been doing doesn't do a good enough job of getting the oxygen out. The article suggested filling the keg with water and then using CO2 to push the water out. This does a better job of removing all the O2 and it uses less CO2 to do it. I'm going to try very, very hard to completely purge all the air out of my keg before I keg the next beer.

It makes more sense than any other theory I've had to date.

One simple thing I've always forgotten is to push the out post while purging. No sense leaving the dip tube full of air that will assuredly get sucked back into the beer even before the headspace air.

ANother is plunging the auto siphon a few times above the liquid level to push the air out of that as well.


Not to say that your problem is oxygenation. Your problems seem to go much deeper than that. BUt just in case some one in a Google search ends up here reading about oxygenation.

Well it appears that was the problem all along. Last Thursday I kegged an amber ale and it's excellent. I purged the keg of CO2 using the method I described above and the beer still tastes great. No hint of the off-flavor that I could detect.

LovesIPA said:

Well it appears that was the problem all along. Last Thursday I kegged an amber ale and it's excellent. I purged the keg of CO2 using the method I described above and the beer still tastes great. No hint of the off-flavor that I could detect.

Click to expand...

So, do you :

1. Fill the keg with starsan
2. Push it out empty using co2
3. Disconnect gas
4. Vent and leave the PRV open
5. Fill the keg using the liquid post, pushing the beer from the fermenter to the keg using co2
6. Close PRV, reconnect gas and pressurize?

If I had a way to hook up my fermenter to a CO2 source that would be a great way to fill kegs but I don't.

What I do:
- Clean and sanitize keg
- Fill with sterile water (the Glacier vending machines sterilize the water with UV light so I used 5 gallons of it)
- Push water out with CO2
- Disconnect, vent, remove lid, cover opening with sanitized paper towel
- Rack to keg using autosiphon
- Reconnect gas, pressurize

LovesIPA said:

If I had a way to hook up my fermenter to a CO2 source that would be a great way to fill kegs but I don't.

Click to expand...

Try this, maybe. Works very well.

Congrats man, hope it finally works out for you! I've been following this thread since before the previous one was closed. It's good to know that persistence and patience paid off. Let us know how the next couple of batches turn out, hopefully problem free!


Sent from my iPhone using Home Brew

The amber ale is still delicious without a hint of the off-flavor. I'm kegging an IPA today. Fingers crossed!

IPA should be a great test as those fragile hop flavors/aromas are much more susceptible to oxidation.

That beer was also oxidized, although to a much lesser degree than my other beers were getting previously. It was actually drinkable, most of the hop flavor and aroma were present, but there was a noticable off-flavor that I'm completely convinced is oxidation now.

After I kegged it, I must have purged the headspace 20 times. Every time I'd walk by the keezer the day I kegged it, I would open it up and purge it. I had it under 30 psi for 24 hours so I can't imagine there was a whole lot of oxygen left in the headspace. But apparently it was enough.

I've been wrestling with the idea of transferring the beer under pressure out of the fermenter and through the out tube of the keg but I haven't yet worked out the details of how I'm going to do that with a plastic bucket.

So how does everyone else keg their IPAs? I can't be the only one this is happening to.

Well, I'll detail my process but based on what you have detailed so far in this thread, I am no more careful than you are. Just to add some credibility, I make a hoppy pale ale (which has been accused of being an IPA more than once) which routinely scores 40+ in contests without ever having a judge note oxidation flavors. So at least for me, I am sure my process works. My friends also rave about my DIPA but I have never entered it in a contest. I have struggled with making a regular IPA, but I'll detail those issue below.

For kegging my beers, I generally pressurize and purge my empty, sanitized keg keg 3-4 times. When I crack it open there is generally a nice CO2 fog in there that keeps me from seeing the bottom. I run sanitizer through my auto-siphon but I don't purge it with CO2 (but I've heard it suggested that you should and may start doing that just in case). I then crack my lid on my bucket fermenter just enough to fit the auto-siphon in there. I don't do this to keep oxygen out, I do it so the lid will hold the auto-siphon in place so I don't have to hold it, but it might help. I then make sure it only takes 1 good pump to get the siphon going. I make sure my hose is near the bottom of the keg (so it become quick submerged) and it flows against the wall of the keg with no splashing. Once done I seal up the keg, purge again 3-4 times and then throw it in the kegerator under pressure, depending on my other needs, sometimes at 30psi for a quick force carb, sometimes at serving pressure for a normal force carb.

Now as I said, I have made delicious, problem free DIPA's and hoppy pale ales, but I was struggling a lot to make a great IPA. I most definitely had a couple of batches ruined by oxidation. This usually happened if I had a violent fermentation that would blow the lid off my fermenter. Every time this happened my IPA would end up oxidized no matter how quickly I caught the problem. I rectified this problem with the combination of blow-off tubes and fermcap-S. As a matter of fact, ever since I started using fermcap-S I haven't even needed the blowoff tube.

Even with that problem fixed I still had a couple of other batches end up oxidized. What I discovered was that I had a couple of bucket fermenters that didn't get a 100% good seal. Common wisdom around here says fermentation should put a nice protective CO2 layer on your beer, but my personal experience was that if I didn't have a tight seal I would have oxidation issues. Now maybe if I transfered as soon as active fermentation was complete I would have been fine, but generally I let my beers sit in the primary for ~two weeks. Maybe once active fermentation was done they started picking up oxygen, I don't know. What I do know is that once I stopped using the suspect fermenters I haven't had an oxidation issue since. Obviously I have some correlation here, but not causation, at least not for sure.

Now I suppose my IPA's could have been picking up the oxygen during the addition of dry hops, but I use the same method all the time. I take the quick-disconnect off a CO2 line, put the line in the airlock hole and turn on the gas. Then I crack the lid just enough to add my hops, seal it back up, let the gas run for another 30 seconds, replace the airlock, done. Works just fine for my other hoppy beers.

Once I solved my oxidation issue, I was still having this "off flavor" in my IPA's that I just didn't like. I would share with friends and they would all tell me they like it, but I just wasn't having it. I didn't think it was oxidation, maybe an ester problem but I was using the same yeast and fermentation temp as my hoppy pale and DIPA, but something just wasn't right to me. Finally I grabbed all my recipes and brew notes to try to figure out what was different about my IPA's that just wasn't working.

Then I noticed a trend, all of my IPA's included Citra hops. Neither my DIPA or hoppy pale had them. I did some research and found a blog entry describing the flavor of Citra as "over-ripe mango" and a light went off in my head. That was exactly what I was tasting and was exactly the flavor I didn't like. Made perfect sense why my friends all told me my IPA tasted fine to them as well, a lot of people really enjoy Citra and it is a popular IPA hop. Rewrote the recipe to exclude Citra and just put the first batch of the reformulated recipe on gas in the kegerator. Based on the hydrometer sample, I think I have finally nailed it, but won't know for sure for another week or so.

Overall, I probably have brewed 10 IPA's that just didn't turn out. Probably lost 5 batches to oxidation then the next 5 were due to my dislike of Citra. Because my sample of beers lost to oxidation is so small, I can't say with a 100% certainty that the fermenters were truly the issue. Could be I was just sloppy in other processes and it is just a coincidence.

But as you can see, my methods aren't much different than yours. First I would make absolutely sure that oxidation is your issue. Maybe you just have a flavor issue that you are misdiagnosing as oxidation. Outside of that, just purge everything with CO2. Purge your fermenter before you crack the lid to put a nice layer in there, purge your auto-siphon, everything. Then purge it all again.

With a plastic bucket, I wouldn't know. If your bucket lid is rigged with a hole for a bubbler, you should give it a try. What the gas does is only start the siphon. Then it fills the bucket to equalize pressure. The container doesn't have to be completely airtight, just tight enough to handle the little extra pressure required to start the siphon.

If it doesn't work, carboys are cheap and I use a carboy cap to fit the racking cane and the co2 fitting. If you're afraid of carboys, just use a better bottle. You can still manage to fit the carboy cap on a better bottle by just taping it to make a quick seal.

Santé!

I've read through the thread, and recommend you post a sample of your next problem batch for us all to taste.

My process is almost exactly the same as yours, right down to the fog in the keg and using the partially removed bucket lid to trap the autosiphon in place. When you have submitted your hoppy pale ale to competitions, was it bottle conditioned? Or was it served out of a tap? I can make great bottled beer, but as we know, bottling sucks.

I don't think the problem is the exposure to oxygen during the racking process. My hypothesis is that the oxidation is occurring from leftover O2 in the headspace after filling the keg. Purging 3-5 times just doesn't remove enough of the air to prevent oxidation. The fact that I tried REALLY hard to minimize O2 with the last IPA I kegged and it was still oxidized but nowhere near as much as previous batches backs this up somewhat.

I brewed Caribou Slobber a few weeks ago and with the oxidation of my latest IPA, I basically procrastinated and put off kegging it because in the back of my mind, it was just going to get oxidized again and I've have to slog through another 5 gallons of so-so beer. I spent the last several weeks thinking about the best way to transfer the beer to the keg and remove all of the oxygen.

Here is what I came up with:

- Rack beer as normal to a clean and sanitized keg. This is the beer keg.
- Fill a second keg all the way to the top with sterile water. I mean ALL THE WAY so there is NO air in the keg, just water.
- Seal the keg off. Also open the PRV until water shoots out to purge the air from the air trapped under the lid.
- Use CO2 to push all the water out of the keg. Now we have a keg that is full of nothing but CO2 - the CO2 keg.
- Hook up a keg coupler (two liquid disconnects and a piece of beverage tubing) to the CO2 keg (liquid side) and vent CO2 out of the other end of the coupler to purge the air out of the coupler tubing.
- Connect the keg coupler and the CO2 to the beer keg (liquid side and gas side, respectively).
- Connect a spare gas side disconnect to the gas keg's gas side to vent as the keg fills.

Now you have a keg that can be full of nothing but beer and CO2. If there is a way for there to be ANY air in the keg I don't see it.

If this works out well, I will try it with my next IPA.

What I can't figure out is why this isn't a more common problem. With how easy it was for me to oxidize batch after batch of beer, I would have thought someone would have worked all this out by now.

I'm certain the problem is oxidation. I've eliminated just about every other possible source of off-flavors, and it perfectly fits everything I've observed and experienced.