Stir Plate Foaming

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crundle

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I have just built myself a tight arse stir plate using a couple of those 'rattlesnake egg' type magnets that I think Ross and several others are using. I have just pitched some yeast from a brew that is fermenting already to see how it goes growing the little buggers, but have some questions that I didn't find an answer to in my rather extensive searching of the interweb over the last few days.

I am using a 500ml pasta jar for this starter, with 250ml of 1.040 wort in it.

Do I need to be concerned about foaming? I was wondering if there is a general consensus as to whether it is necessary if the stirring vessel is over a certain ratio compared to the starter volume.

Secondly, should the stirrer be run constantly or not? My thoughts were that running it constantly might help break down the foam if it forms, but I could be very wrong on this score.

I have a slight whirlpool effect happening, am I correct in thinking that it only needs to be moving to help introduce oxygen and disperse CO2, or do you get some benefit by having the thing looking like a tornado? The magnet is set to stir nice and quietly, which is a big factor with SWMBO, along with not foaming all over the place.

Thanks for any help you can provide,

Crundle
 
No concern re: foaming

As long as its not Krausen shooting out the top and all over the place - SWMBO wont be happy with that!

Constant stirring is the way to go, constant activity that way.
 
I am using a 500ml pasta jar for this starter, with 250ml of 1.040 wort in it.

Firstly look at getting a bigger vessel. If you want to build up a decent size starter to create enough yeast to pitch you'll need, very generally and roughly speaking, a starter size of ~1.5L for ales and ~2.5L for lagers

Do I need to be concerned about foaming? I was wondering if there is a general consensus as to whether it is necessary if the stirring vessel is over a certain ratio compared to the starter volume.

Depends on the yeast, I've found aggressive fermenters like Belgians go close to climbing out of my 3L conical flask but lager yeasts barely register a blip.

Secondly, should the stirrer be run constantly or not? My thoughts were that running it constantly might help break down the foam if it forms, but I could be very wrong on this score.

I have a slight whirlpool effect happening, am I correct in thinking that it only needs to be moving to help introduce oxygen and disperse CO2, or do you get some benefit by having the thing looking like a tornado? The magnet is set to stir nice and quietly, which is a big factor with SWMBO, along with not foaming all over the place.

It's more to do with getting as much O2 into and CO2 out of your starter as possible to promote yeast growth. Given that is the case you should have it on all the time going with a "reasonable" vortex to acheive the above. Note some will switch off the plate towards the end of fermentation to ensure the majority of O2 in the starter is consumed by the yeast and they then pitch whole solution into their wort, and thereby avoid pitching oxydised tasting beer into their wort. I prefer to keep it on till the end of fermentation, chill the resultant solution for a day or two, pour off the resulting "beer" and pitch the settled yeast into my brew.
 
Thanks for the feedback.

I am planning to step this 250ml starter up to a 2l erlenmeyer when I get it tomorrow, but just started freaking out thinking that I might have foam everywhere by then if I didn't use anti-foam.

My plan is to use a 2l starter for ales and do 2x2l starters for lagers, and chill them to flocculate and concentrate the yeast, giving it a little spin on the stirrer while warming up the yeast to get it going again.

cheers,

Crundle
 
Erlenmeyer Flasks are recommended for stirplates as they have a flat bottom (no annoying clinking noises on the stir), allow plenty of headroom and can be heated up for sterilising (unlike a jar which would crack).

Ross at Craftbrewer has a range of them or any Scientific Supply store (most unis science depts have one). We recently did a build on these stirplates at my club and most of the guys were buying 2L Erlenmeyers for ales and 5L for Lagers and belgian gushers.

Hopper.
 

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