Airstone Usage - What To Do?

[BOG]

My last 2 batches died early so I've decided to try an airstone to keep the yeast alive longer, ferment faster and finish dryer.

So, what's the common practice with Airstones?
how long do you run it for?
When should you not run an airstone?
How do you deal with bad stuff being pumped into the wort?
What in general is the result , Positive or negative?


Thanks

BOG

 

[matt white]

Mate in my experience they make no difference, a shake before pitching will do...that is hard to scientifically prove of course and I am sure many will beg to differ.

I reckon its just another infection invitation.

Maybe something else is causing the attenuation problems.

 

[Greg Lee]

BOG,

there's some good info in the latest US brew mag "Brew Your Own" July/August 2009 edition (Vol. 15 No. 4) - there's articles on both "Wort Oxygenation" and "Attenuation". I picked it up the other day from the local newsagent along with the usual Aussie Beer and Brewer mag, its definately worth a look at around $6.95...

Cheers,
Greg

 

[chappo1970]

So, what's the common practice with Airstones?

I run mine off pure Oxygen. I simply connect it up once the wort is at pitching temp. Sterilise. Drop it to the bottom of the fermenter and turn on the Oxygen so it just bubbling and run it for 2 mins which seems to be the consensus in achieving 20ppm O saturation

how long do you run it for?

2 mins

When should you not run an airstone?

When you use olive oil as an aerator for lipids but that's another arguement

How do you deal with bad stuff being pumped into the wort?

If you use an air pump I think there is a hepa type filter? I'm 100% on this as I use bottled oxygen.

What in general is the result , Positive or negative?

Great sure fire way to getting a cracking start.

Cheers

Chappo

 

[beerbrewer76543]

Here's a good podcast on the topic:

"August 7, 2008 - Aeration: Shaking vs Pumping" at Basic Brewing Radio

Click on the "Streaming mp3" tab to download the mp3 file (11.8Mb)

If I remember rightly the airstone performed very poorly whereas rocking the fermenter back and forth for 5 minutes achieved 95% oxygen saturation

edit: added file size

 

[BOG]

The issue I have is that the last 2 brews started at 1.065 and dropped off at 1.030.

one with Nottingham one (porter) with Belgium Ale yeast (Pale Ale).

I pitch a full 1 litre starter (3 days into ferment) into 15L of wort that's at High Krausen and the stuff still dies off.
I have a temp controlled fermentation fridge.
I am using no chill with the wort hot from the kettle into the cube and left on the top step of the swimming pool for 24 hours. The pool is at 18 deg.

I was thinking an airstone could be switched on and off over a few days to keep the yeast in Aerobic state for longer then turn it off for fermentation to finish.
Hoping this will create a more vigourious ferment and have it chew more sugar before getting lazy and dropping.

Is the theory sound?

Can you run the airstone on low for days or is it only used for a few hours.


BOG

 

[Hogan]

If you are using oxygen run the stone for 30 seconds to a minute, otherwise you over-oxygenate.

If not using oxygen then run it as long as you like, but use a filter. You will have to stop anyway when the foam runs over the top of the fermenter. Do it cold and the O2 will stay in solution longer than at 20c.

If I remember rightly the airstone performed very poorly whereas rocking the fermenter back and forth for 5 minutes achieved 95% oxygen saturation

I would suggest that there is no way to achieve 95% oxygen saturation by this method. This is O2 in the atmosphere you're talking about - not pure oxygen, no way. IMO.


Cheers, Hoges.

 

[Ash in Perth]

You dont want 95% saturation anyway. Aeration levels are not critical but can make differences. High O2 will reduce ester formation, low O2 encourages esters but it also depends on your yeast. The old fermenter-fermenter pour trick will give enough for fermentation when you are using a healthy yeast culture.

I usually use an air stone for the duration of my fermenter filling from my heat exchangers so 5-10min (ale-lager temps). to keep it sanitary, a small inline 'sterile' filter is ok. Just keep your air stone and a length of hose in 80degree+ water for 10min or so. I just chuck mine in my hot liquor tank for a while. This is not perfect but it works very well for me.

Hope this helps mate.

PS. Does any one else find it strange that a spell-check on a home brew site does not know the correct spelling of 'fermenter'.

 

[Screwtop]

The issue I have is that the last 2 brews started at 1.065 and dropped off at 1.030.

one with Nottingham one (porter) with Belgium Ale yeast (Pale Ale).

I pitch a full 1 litre starter (3 days into ferment) into 15L of wort that's at High Krausen and the stuff still dies off.
I have a temp controlled fermentation fridge.
I am using no chill with the wort hot from the kettle into the cube and left on the top step of the swimming pool for 24 hours. The pool is at 18 deg.

I was thinking an airstone could be switched on and off over a few days to keep the yeast in Aerobic state for longer then turn it off for fermentation to finish.
Hoping this will create a more vigourious ferment and have it chew more sugar before getting lazy and dropping.

Is the theory sound?

Can you run the airstone on low for days or is it only used for a few hours.


BOG

Is the theory sound?

Lots more to attend to before yeast condition. Are you confident that you have good fermentable wort, did you use extract, or if AG what was the percentage of dextrinous malt (cara/crystal) in your grist bill, what was your sacch rest temp, did you use direct heat for the mash, did you add hot water to the grist or did you add hot water to your mash tun and allow for thermal absorbtion before adding the grist.

Got the picture? Plus a starter with Nottingham, what were you thinking? If nottingham gave out at 53% apparent attenuation then either your fermentation temp is fluctuating or your wort is high in unfermentables. If the temp drops overnight the yeast will drop out.

In any case to answer your question, aerate prior to pitching and again at 24hrs so long as there is no active fermentation. Aerating active fermentation = oxidised starter or beer, adding oxidised starter = oxidised beer. Aeration of Liquid Yeast pays benefits in higher apparent attenuation, do a test, split up your wort into two fermenting vessels. Aerate one fermenter using a big chefs whisk and don't aerate the other you will see the results in the FG. Filters are available if using a pump and airstone.


From Experience: Don't make starters using dried yeast and don't aerate dried yeast. Or do, and add to your experience.


Cheers,

Screwy

 

[Ash in Perth]

Good advice there Screwtop...

I have never aerated after pitching but it is common in commercial brewing (big end) to knock back ester production in high gravity brewing. I believe it also gives yeast a big boost in their activity.

 

[warra48]

I use an aquarium pump in building up my starters. I run it without the airstone, otherwise I'd have foam climbing out the top in 1 or 2 minutes. Without the airstone, using just the tube through a filter, it certainly aerates the starter and keeps the wort in constant agitation, similar to what a stir plate would do. I run it for 5 to 6 hours, then switch it off and allow it to ferment out. There is a noticible increase in yeast produced this way compared to allowing the starter to take its own course.

For my fermentations, I use the airstone. I can run it for 10 to 15 minutes before the foam tries to crawl out the top. I pitch my yeast at the start of it so it gets a good stirring as I aerate.

It works for me. I pitched the slurry from a 7 litre starter of WY2001 late yesterday into a BoPils, both at 9C. By this afternoon I already had a 3 to 4 cm kraeusen layer, so there was no delay in taking off.

 

[BOG]

Thanks for all the replys,

Screwy I think your on the mark.(again!),

AG brew, no sac rest, heated mash water above required temp.
Loaded mash tun without grain and waited for the esky to absorb the heat then open the lid to let the mash water cool to strike temp.
Mash in , test for correct mash temp then close the lid. (65deg mash temp) I loose about 2 - 3 deg over the 60 minute mash.

Yes , Nottingham with a starter, hell of an idea but woosh off she goes. Still not out the top but a big Krausen.
Hence why I'm thinking something else is wrong because that stuff is ferocious and should gobble up a brew in a few days.
Yes I do the swirl etc to keep it in suspension but the stuff just drops early.

I believe you may have a point with unfermentables. Let's chase that idea.

Back to basic theory for me here. Hotter mash temp = higher or lower unfermentables? Higher = dryer yes ?

Here's the build for the belgium p.a. Re your comment of % of Crystal etc. Comments?

2.00 kg Pilsner (2 Row) Ger (3.9 EBC) Grain 43.01 %
1.00 kg Munich Malt (17.7 EBC) Grain 21.51 %
1.00 kg Vienna Malt (7.9 EBC) Grain 21.51 %
0.50 kg Cara-Pils/Dextrine (3.9 EBC) Grain 10.75 %
0.15 kg Crystal, Dark (Joe White) (216.7 EBC) Grain 3.23 %
13.00 gm Northern Brewer [10.00 %] (60 min) Hops 17.4 IBU
20.00 gm Saaz [4.00 %] (15 min) Hops 5.3 IBU
20.00 gm Styrian Goldings [5.40 %] (5 min) Hops 2.9 IBU
1 Pkgs Belgian Golden Ale (White Labs #WLP570) Yeast-Ale

Can you explain further the comment re: oxidised starter. How does a plate stirer work if it's not difusing oxygen into the starter constantly?
Sound like I've been buggering up my beer with my starter also....

BOG

 

[Screwtop]

Thanks for all the replys,

Screwy I think your on the mark.(again!),

AG brew, no sac rest, heated mash water above required temp.
Loaded mash tun without grain and waited for the esky to absorb the heat then open the lid to let the mash water cool to strike temp.
Mash in , test for correct mash temp then close the lid. (65deg mash temp) I loose about 2 - 3 deg over the 60 minute mash.

Yes , Nottingham with a starter, hell of an idea but woosh off she goes. Still not out the top but a big Krausen.
Hence why I'm thinking something else is wrong because that stuff is ferocious and should gobble up a brew in a few days.
Yes I do the swirl etc to keep it in suspension but the stuff just drops early.

I believe you may have a point with unfermentables. Let's chase that idea.

Back to basic theory for me here. Hotter mash temp = higher or lower unfermentables? Higher = dryer yes ?

Here's the build for the belgium p.a. Re your comment of % of Crystal etc. Comments?

2.00 kg Pilsner (2 Row) Ger (3.9 EBC) Grain 43.01 %
1.00 kg Munich Malt (17.7 EBC) Grain 21.51 %
1.00 kg Vienna Malt (7.9 EBC) Grain 21.51 %
0.50 kg Cara-Pils/Dextrine (3.9 EBC) Grain 10.75 %
0.15 kg Crystal, Dark (Joe White) (216.7 EBC) Grain 3.23 %
13.00 gm Northern Brewer [10.00 %] (60 min) Hops 17.4 IBU
20.00 gm Saaz [4.00 %] (15 min) Hops 5.3 IBU
20.00 gm Styrian Goldings [5.40 %] (5 min) Hops 2.9 IBU
1 Pkgs Belgian Golden Ale (White Labs #WLP570) Yeast-Ale

Can you explain further the comment re: oxidised starter. How does a plate stirer work if it's not difusing oxygen into the starter constantly?
Sound like I've been buggering up my beer with my starter also....

BOG

How about temp control??

That recipe has 14% dextrinous malt, plus 65 Sacch rest....game, yeast would have to be in good nick and a big pitch to achieve good attenuation. Stir plate draws air into the starter wort via the vortex, continue to stir once fermentation has begun and you'll oxidise the starter wort. Plenty of info to be researched re conversion and Alpha and Beta temps and results, basically, lower temp = drier beer and a little better attenuation, nothing like some of the bullshit you will see on here, but a few points.

Dried yeast starter........................ :unsure: why, are you using less than the recommended pitching rate?

Cheers,

Screwy

 

[BOG]

Ok, confused... but learning.

Temp control. yes , temp controller fermentation fridge. 18 deg +/- 1 deg. I bumped it up to 20 deg for the last week to see if the raised temp helps.

So the Carapils and Crystal wont ferment out ?
Beersmith dosn't calculate that. How do you calcualte the final gravity based on your percentage of unfermentables?
That reciepe was actually 1.051 starting. Beersmith calcualtes it as finishing at 1.016. That's obviously not right.

Big starter , yes hence the nottingham in a 1 Litre starter at high krausen rather than just pitch the dry yeast. (11 g packet - Ross's re-pack yeast)

So a stirplate doesn't keep running? didn't know that that. I though you just turned them on and pitched sometime later. (note to self for later)

What mash temp do you recommend? It's at 65deg now. Others seem to use 67 or 68 hence my confusion.


BOG

 

[Screwtop]

Ok, confused... but learning.

Temp control. yes , temp controller fermentation fridge. 18 deg +/- 1 deg. I bumped it up to 20 deg for the last week to see if the raised temp helps.

So the Carapils and Crystal wont ferment out ?
Beersmith dosn't calculate that. How do you calcualte the final gravity based on your percentage of unfermentables?
That reciepe was actually 1.051 starting. Beersmith calcualtes it as finishing at 1.016. That's obviously not right.

Big starter , yes hence the nottingham in a 1 Litre starter at high krausen rather than just pitch the dry yeast. (11 g packet - Ross's re-pack yeast)

So a stirplate doesn't keep running? didn't know that that. I though you just turned them on and pitched sometime later. (note to self for later)

What mash temp do you recommend? It's at 65deg now. Others seem to use 67 or 68 hence my confusion.


BOG

Beersmith calculates extract contribution (sugar), for the malts you select for your recipe. It calculates this from the malt specs contained in the Malt database (you can change these figures if you have up to date malt specs, but that's another issue). It can not distinguish between highly fermentable and non fermentable sugars. Also Beersmith calculates average attenuation based on the attenuation spec for the yeast you have selected in your recipe from the specs contained in the Yeast database. This attenuation figure can also be changed the same as the malt specs. However knowing what attenuation you will achieve from a specific malt bill using a specific yeast, how it is treated and how it is fermented is all a matter of experience. Yeast attenuation results depend upon fermentability of the wort, if a yeast company states a range of attenuation say between 70% - 75% then you would expect that 75% would be achievable using base malt only mashed on the lower end. Adding Cara/crystal malt lowers attenuation the same as increasing mash temp. Although mash temps naturally do not have as great an impact on attenuation as less fermentable sugars in the wort. Yeast condition and viability can also affect attenuation.

Since you do allow for mash tun heat absorbtion then I don't see you having issues with mash temps, 66 is a good starting point, however I rarely if ever mash above 66 and more often mash at 64.