Stir plate advice needed

[Ray1314]

Hi guys

Was attempting my first ever yeast starter, bought 2 Intllab stir plates (both came with a 1 inch stir bar) a 2l conical flask and a 3l conical flask.

Problem is that I can’t get a whirlpool going in the 3l flask?

Does anyone know if a bigger stir bar would fix the problem?

 

[steveinUS]

My goal with a stir plate is to just keep it all moving so that the yeast is in continuous contact with food and nutrients. No whirlpool is necessary as long as the bar is still spinning (hasn’t gotten thrown off) and the entire starter is circulating.

 

[hedgerowpete]

ihave one inch in 500ml and a litre flasks
2 inich for 1 litre to two litres flasks
i dont have a 3 l flask, but would have thought to go a lot larger than you have

 

[strange-steve]

I'd always heard that the main goal of the stir plate is simply to keep the yeast in suspension, but Braukaiser did an interesting experiment on this (here) and found that contrary to popular belief stir speed and agitation is correlated with yeast growth. An oversized flask/stir bar with a full vortex seems to be the way to go.

 

[foxbat]

Typically the stir bar that comes with the plate is the ideal size because the magnets at each end of the bar align directly with the magnets below the plate. If you get a bigger bar then the magnets won't align as well and you're more likely to throw the bar meaning you have to run it at a reduced speed that negates the point of getting the bigger bar in the first place. Have a look inside the stir-plate to see how it's put together. You may be able to adjust the position of the spinning magnets.

 

[Richie_asg1]

Is the vortex a good idea because it introduces more oxygen?
...One of my many projects as yet unstarted.

 

[strange-steve]

Is the vortex a good idea because it introduces more oxygen?
...One of my many projects as yet unstarted.

That's the very point, the starter is to propegate yeast not make beer.

 

[hedgerowpete]

yep, i thought whirl pool was to introduce disolved O2 aswell

 

[Ray1314]

Thanks for all the posts guys. In the end I did get it to work, but only by starting with a small amount of liquid in the 3l flask, slowly adding extra wort.