Comparison Of Aeration Methods

[huscre]

Hi, I'm planning my first AG system (HERMS) and trying to decide how to handle aeration after transferring from brewkettle to fermenter (via a chiller).

One method I've seen uses an aquarium pump and an airstone hanging inside the fermenter, and another option is to use a siphon spray wort aerator which goes in the end of the pipe and kinda splashes the chilled wort as it enters the fermenter.
(http://www.craftbrewer.com.au/shop/details.asp?PID=968)

Can anyone advise me of any reasons to go "all out" with the aquarium pump and stainless steel airstone, or even reasons I should stick to using the simple siphon adapter? Also do I risk introducing bacteria to the cool wort by pumping air through it?

I already have a spare aquarium air pump so the price difference isn't all that significant, but it still seems like a bit of a hassle running an extra electrical device if a little $5 plastic gizmo will do the same job.

 

[jjeffrey]

In my view, aquarium pumps are a waste of time. Sticking tubes into and out of a fermenter filled with fresh sweet wort with the lid half off is an infection hazard. There are 2 standard sizes of airstone available- I think 2 micron and 0.5 micron. The aquarium pump will not have enough guts to pump through the 0.5 at any decent rate. The 2 micron will not filter microbes from the air, so if you consider it necessary to have clean air you will need an air filter as well. Airstones are difficult to clean properly and gum up after a while. The ones I've had also rust- especially if you use halogenated sterilisers (bleach, iodophor, anything with "chloro", "iodo" or "bromo" in it).

Air induction by flow into the fermenter is WAY easier and simpler. Never seen the flash splashy gizo but I reckon its a good idea. I just put the fermenter under the kettle tap and let it run in as fast as possible until I get near the top of the trub cone in the kettle (then it's whoa boy). This goes without saying, but you need to make sure you do your transfer in a clean environment (no vacuuming, fans, heaters or any other blowy/dusty environments) as you can't ensure that the air is clean and there is an increased risk of infection. My measurements have indicated that this method works well for batches less than 40L (on my kit, anyway). Extra air was required when I went above 40L as the dissolved oxygen seemed to drop off (but that was a new setup).

A good, healthy, well oxygenated yeast starter can make up for lower oxygen levels in the wort- you can provide a population large enough to ferment your batch and it's easier to introduce air to a small starter. The oxygen is so the yeast can build strong healthy cell walls. If your yeast population is large enough and already has good healthy cell walls, DO in the wort becomes of lower significance.

jj.

 

[huscre]

Hey JJ,

Thanks for the awesome response. I'll stick to the simple method then (without an airstone). I'm only planning on making 20L batches in the system, and all the extra cleaning/clogging/rusting risk with the airstone sounds like too much of a hassle. Great to hear this will be satisfactory for my needs.

Also thanks for the theory behind DO.

Regards,
Mick. :icon_cheers:

 

[felten]

Yeast need oxygen for strong cell walls? I thought they needed it to reproduce.
IE: http://www.howtobrew.com/section1/chapter6-9-2.html

 

[Adamt]

Yeast need oxygen for strong cell walls? I thought they needed it to reproduce.
IE: http://www.howtobrew.com/section1/chapter6-9-2.html

Part of reproduction is building cell walls.

 

[hefevice]

Yeast need oxygen for strong cell walls? I thought they needed it to reproduce.
IE: http://www.howtobrew.com/section1/chapter6-9-2.html

To reproduce effectively (and survive in a hostile environment) they need strong healthy cell walls. The sterols and unsaturated fatty acids referred to in the first sentence of your link are used to build the cell walls.

The cell wall is reduced (and progressively damaged) each time the yeast buds and splits during reproduction. Once the yeast gets into anaerobic respairation (i.e. fermenation), cell wall can no longer be repaired (i.e. sterols and fatty acids can no longer be produced).

The thicker the cell walls, the better the ability to handle osmotic pressure (resulting from imbalace of chemical concentrations inside and outside of the cells), and the better the yeast will survive in a high alcohol environment (which is potentially toxic to the yeast).

 

[BOG]

I just use a small sheet of metal (clean and Sterile) hanging inside the fermentor at an angle.

The wort from the Heat Exchange is drained slowly (10 min to fill fermentor) across the sheet providing plenty of surface area to pick up oxygen.

Works like a wine decanter. More surface area more air touchs the wort.

Simple, cheap and very effective.




BOG

 

[Bribie G]

I've been using yeasts which require a fair amount of rousing and oxygenating such as Wyeast West Yorkshire Bitter and Wyeast Ringwood and I find a perfectly good aerating tool for about five bucks is one of these.



It makes a great paddle for aerating and you can see the wort whooshing through the holes as you go. Reject shop or Sams Warehouse have heaps of them. Graham Wheeler in his real ale book recommends beating ale yeasts of the Northern Variety twice a day for a few days. For other yeasts I usually just thrash them the once and they seem to take off great.

 

[Smashin]

huscre,

As with all things there will be many and varied opinions on this, thought i'd share my setup of which I haven't lost a batch to infection. I find it fairly straight forward and easy to use and maintain.


Standard fish tank pump ==>
Inline filter cartridge - filled with polyester fluff (fish tank filter grade) which is soaked in Starsan ==>
2um Stainless Steel air stone.


The air stone fits inline between my counter flow chiller and the fermenter.


As with every thing in my brew day, from kettle to fermenter gets a warm PBW soaking for ~30min followed by starsan soaking ~15min (times vary but all this is done during the boil). With no air in the system the wort chases right behind the starsan through the chiller into the fermenter (starsan is blead off before the fermenter).

My experience with the 2um air stone has been unfaulted as it has brought me no problems. After each use i back flush and soak the air stone in hot PBW in a sealed container between brew days. Every few weeks the stone gets a ~20min boil in a strong PBW solution and this seams to restore the air flow back to original, not that its ever significantly blocked up but i do notice the increased air flow after.

The air filter setup works a treat, it cheap, easy to use and maintain and doesn't restrict the air flow like 0.2um expensive in line medical air filters (been there). As I said I'm yet to looses a batch to infection (~100 brewdays with this setup). From kettle to fermenter is sealed so again minimising the risk of infection. I used to put the yeast in first and let the chilled wort run onto it, i have since given this away only based the theory of preventing light strike on the yeast. So the lid comes off the fermenter once to add the yeast and to give it a quick stir before being looked after by this baby.


The ultimate in Temp control bar none (imo). :icon_drool2:

Smashin

 

[huscre]

Nice setup smashin!

Thanks for the ideas and anecdotal feedback.

Cheers.

 

[drsmurto]

Pitch a healthy, large, well oxygenated starter.

5g of yeast nutrient in last 5 mins of boil

Run wort thru chiller which then feels the force of gravity..... drops from a height of ~1m to the fermenter. Splash!

I have action in the fermenter in 2 hours for some yeasts!

Even for yeasts such as west yorkshire or ringwood, no extra effort is made. No whipping of the yeast during fermentation.

Once the lid/clingwrap is on, my job is done. :lol:

 

[muckanic]

The 2 micron will not filter microbes from the air, so if you consider it necessary to have clean air you will need an air filter as well.

There is a school of thought that floating microbes aren't the problem; it is more dust particles. Some of the gruntier air pumps come with a filter pad on the intake side. The cheaper ones just draw air in through any available gap in the housing. With a bit of messing around, it is possible to run the air line into a closed fermenter that subsequently develops positive pressure. OTOH, plenty of folks perform and indeed prefer open ferments, air pump or no air pump.

Air induction by flow into the fermenter is WAY easier and simpler.

Many moons ago, a guy on HBD tested that idea with a DO meter. He found that 5 pours back and forth were needed to get maximum effect and to approach saturation. IIRC, the first drop contributed about 50% of the total. He didn't however test the effects of using bubbling devices like venturis, sprays, etc. As far as I am concerned, 25L is the weight limit for pouring anything back and forth by hand.

 

[Bribie G]

.......................................
Even for yeasts such as west yorkshire or ringwood, no extra effort is made. No whipping of the yeast during fermentation.

Once the lid/clingwrap is on, my job is done. :lol:

I thrashed your Landlord. Loved every minute of it.
So did the Landlord

 

[drsmurto]

I thrashed your Landlord. Loved every minute of it.
So did the Landlord

:lol:

I bet you did.....

 

[pbrosnan]

In my view, aquarium pumps are a waste of time. Sticking tubes into and out of a fermenter filled with fresh sweet wort with the lid half off is an infection hazard. There are 2 standard sizes of airstone available- I think 2 micron and 0.5 micron. The aquarium pump will not have enough guts to pump through the 0.5 at any decent rate. The 2 micron will not filter microbes from the air, so if you consider it necessary to have clean air you will need an air filter as well. Airstones are difficult to clean properly and gum up after a while. The ones I've had also rust- especially if you use halogenated sterilisers (bleach, iodophor, anything with "chloro", "iodo" or "bromo" in it).

Air induction by flow into the fermenter is WAY easier and simpler. Never seen the flash splashy gizo but I reckon its a good idea. I just put the fermenter under the kettle tap and let it run in as fast as possible until I get near the top of the trub cone in the kettle (then it's whoa boy). This goes without saying, but you need to make sure you do your transfer in a clean environment (no vacuuming, fans, heaters or any other blowy/dusty environments) as you can't ensure that the air is clean and there is an increased risk of infection. My measurements have indicated that this method works well for batches less than 40L (on my kit, anyway). Extra air was required when I went above 40L as the dissolved oxygen seemed to drop off (but that was a new setup).

A good, healthy, well oxygenated yeast starter can make up for lower oxygen levels in the wort- you can provide a population large enough to ferment your batch and it's easier to introduce air to a small starter. The oxygen is so the yeast can build strong healthy cell walls. If your yeast population is large enough and already has good healthy cell walls, DO in the wort becomes of lower significance.

jj.

I've used an aquarium pump and SS airstone for the last 50 or so brews and never had a problem with infection. I don't really know how much difference it makes but most of the texts seem to encourage aeration. My method is to dangle the stone in the fermenter via a hole in the lid used for the temp probe so the exposure to the atmosphere is minimal. I used to be quite paranoid about exposing the fresh wort to the air however over time I've become less so mainly because I figure that the yeast in a starter vastly out number the microbes in the air that may land in my wort. IMHO most infections are going to come from badly sanitised gear.

 

[jjeffrey]

I've used an aquarium pump and SS airstone for the last 50 or so brews and never had a problem with infection. I don't really know how much difference it makes but most of the texts seem to encourage aeration. My method is to dangle the stone in the fermenter via a hole in the lid used for the temp probe so the exposure to the atmosphere is minimal. I used to be quite paranoid about exposing the fresh wort to the air however over time I've become less so mainly because I figure that the yeast in a starter vastly out number the microbes in the air that may land in my wort. IMHO most infections are going to come from badly sanitised gear.

yeah. I was trying hard in that post not to over emphasize the infection bit, what i said was they were hard to clean (I really hate cleaning, but can't stand dirty stuff). I wouldn't be providing honest information if I didn't indicate that the risk of infection was increased, which it is. It is tho, very low if you are good on your cleaning practices. I personally also take a lay back response to infection risk (given I'm like most other HBers and keep everything spotless), but really I find airstones a pain in the arse when its easy to just run it into the fermenter and not have to worry about anything else. As you point out- most infections do come from badly sanitised gear. Hence, less gear=less work.

Don't get me wrong- each to their own. I personally don't like them for all of the reasons I outlined in my original post (especially since the SS tends to be low grade and be more likely to impart metallic flavours to my beer because of rust)- but I really don't mind if you use yours

Aeration does make a big difference, given that you drive all the oxygen out when you boil (K&K are thus exempt and usually don't need to worry). My personal measurements indicate that with 23L I get about 5-6ppm if I drop it in from the kettle. I can get up to 8 ppm if I let it bubble for an hour or so on the stone and aq. pump.

Over 40L, the airstone takes HOURS. 3-4ppm if I drop it in from the kettle (induction), which is on the low side. Over 40L, I use an air compressor, dryer, coellecience filter (spelt wrong but too lazy to spell check) and a 0.2 micron filter, via a sparge. 8ppm in 20minutes. BTW- the filters are there to remove mainly OIL and other condensed gases.

Smashin- that is a cool setup dude. Nice one.

 

[hefevice]

Run wort thru chiller which then feels the force of gravity..... drops from a height of ~1m to the fermenter. Splash!

+1.

Worth a listen is the keynote address by Ken Grossman to this years NHC which can be found here.

In the early days of establishing the Sierra Nevada brewery, Ken was having problems with batch consistency (threw out 12 batches!!). He finally isolated the cause of the problem to lack of oxygen in the wort (even with open fermenters). Fixed it by simply crimping the end of the inlet hose to the fermenter so that the wort was effectively sprayed into the fermenter in a fan shape.

That being said, there may be a case for additional oxygenation in the fermenter prior to active fermenation for high gravity worts.

Edit: Grammar

 

[muckanic]

I used to be quite paranoid about exposing the fresh wort to the air however over time I've become less so mainly because I figure that the yeast in a starter vastly out number the microbes in the air that may land in my wort. IMHO most infections are going to come from badly sanitised gear.

Well at the risk of getting a bit picky here, I would say that the most common cause of typical wild yeast infections is actually a long lag phase, something which airstones obviously counteract. The second most common cause would be infected starters, ie, the infection was unintentionally added to the brew. Next would be infected equipment, although in practice that usually means equipment that hasn't been cleaned properly in some inaccessible area. Even further down the list would be equipment that is clean yet somehow unsanitised, with the usual bogeys being tap water residue, air contact, and God knows what else.

I might be persuaded to change my tune somewhat if lots of folks were experiencing late-emerging infections months down the track, but in general they know all about it by the middle of fermentation. In other words, they experience wort spoilers and not beer spoilers.

 

[Sammus]

I use an aquarium pump with a 2 micron stone with no filter and have never had an infection. Turn on the pump, stick the stone and tube in your sanitizer, take it out and dunk it straight into your ferementer, leave it till its near bubbling over, then pull the hose out and straight into your jug of sanitizer again, then pull it out and rest it on a paper towel - all while its running, and wait till it dries before you turn it off.

 

[muckanic]

I personally don't like them for all of the reasons I outlined in my original post (especially since the SS tends to be low grade and be more likely to impart metallic flavours to my beer because of rust)

Yeah, I must admit I don't quite get the preference for S/S stones. There is no obvious reason why a cheapo ceramic stone would be any harder to sanitise, with the main drawback being that the pores are probably coarser. Too bad, it is not as if we are using the stone as a filter (or is that what you were getting at a couple of posts back)? The $0.50 ceramic jobs are cheap enough to discard every brew if someone can't be bothered bubbling them in something to clean them out. Given that the vast majority of cleaner-sanitisers are both caustic and oxidative, a non-metallic stone might well have more longevity. The thing that bugs me when I stop to think about it is the glue holding the inlet fitting on. Possibly a good reason not to run the stone in alcohol.

Over 40L, the airstone takes HOURS.

Well the obvious question is what flow-rate pump, and do you have a big enough stone to match? In order to get a pump with an integral intake filter, I had to buy one that is recommended for something like 100L aquariums. I mainly use mine for starters, and I had to fit a valve in the air line to slow it right down.