I received a DIY Magnetic Stirplate Kit from DigitalHomebrew.com the other day and documented this stirplate build and review. I am really impressed with this kit. It’s the first of it’s kind that I have seen. Typically you need to either buy a stirplate or build it using spare parts.
Prior to seeing this, the easiest method was to use the Thermaltake USB fan as I did in my post here: DIY Stir Plate for Homebrew Yeast Starters. But this contains all the parts needed in one bag (minus the enclosure). PLUS the magnets come affixed to the fan and tuned to the included stirbar. I’d have to say the hardest part of my Thermaltake build was getting the HDD magnets centered for the stirbar I chose.
While the “kit” I previously used from Thermaltake included many of the parts needed to make a magnetic stir plate, this kit includes everything but the enclosure.
That means, in the bag, you get: computer fan with two rare earth magnets properly centered and fixed to the fan, a potentiometer to control the speed that also serves as an on/off switch, an LED power indication light, a stir bar, and a power supply.
Up until now I have only used dry yeast for my homebrew creations. This limits me in what types of brews I can create as the various strains of liquid yeast far outnumber the dry strains. As an example, I am planning to brew a Kolsch soon, and there is no available dry yeast strain for that.
The purpose of a yeast starter is to build up the number of viable yeast cells from the amount that comes in a vial of yeast from the store. A vial of California Ale Yeast (WLP001) will have roughly 96 billion yeast cells. For a 5.5 gallon beer with a 1.050 original gravity, you will want to use about 192 billion. A starter is a mini fermentation that builds up the yeast as they feed on the sugars in the mash you’ve made.
A magnetic stir plate escalates the growth in the yeast starter by spinning a magnetic stir bar at the bottom of the flask containing the starter. I can grow that 96 billion to 192 billion with a .75 liter starter on the stir plate, opposed to 131 billion without. These numbers we calculated from the beersmith app.