Stir Bar being tossed around at higher speeds

pietro · April 24, 2013, 7:11pm

Not that its a huge worry, because my starters grow quickly and pretty vigorously when I run it at half speed, but I wanted to see if anyone had experimented with different-sized stir bars. My stir plate isn’t the best, its basically a home-made one that a dude sells on the internet, and he sent my friend two for some reason (score). I get a decent vortex/cone going, but if I really want it to churn, it spins out on me.

I am wondering if any of the particularly magnetically/mechanically-inclined posters had any experience with whether my PC fan needs a stronger magnet, or maybe a bigger/stronger stir bar might be worthwhile.

airlocksniffer · April 24, 2013, 7:17pm

I have one from stirplates.com (now Brewers Hardware but they don’t sell that anymore). Same thing, highest speed throws the bar. I turn it up enough just to see a small dimple in the surface. I don’t believe there’s any big difference between a large and small vortex in terms of yeast growth.

loopie_beer · April 25, 2013, 12:32am

^^^^ This. You really only need enough agitation to keep the yeast in suspension. In fact, and I could be wrong about this, but too much agitation can be detrimental to the yeast’s cell walls.

pietro · April 25, 2013, 2:34pm

Interesting. Good to know. This thing generated a beast of a krausen in my starter yesterday, so I think I have a really solid pitch.

It just looks sexy to have a massive vortex I guess :cheers:

loopie_beer · April 25, 2013, 11:56pm

I know… it is always cool to see that vortex. BUT, for a couple batches I didn’t have a stir plate and people looked at me oddly when I would go to their house with my starter and sit there and shake it… Having a stir plate is much sexier than that! :lol:

tom_b · April 26, 2013, 7:08pm

I agree that you don’t have to have it spinning very fast. I get just enough of a vortex going to get a deep dimple in the surface of the starter.

Also, consider whether your stir bar is too large. They come in different sizes. Most sold for home brewing use a 1 inch stir bar. A 1.5 inch stir bar meant for larger stir plates will make more noise and not spin in the center of the flask well (as I learned when buying a replacement bar).