Looking into making DIY stir plate for 10gal batches

Hi. I am thinking about making a stir plate to improve yeast cell count before pitching. Most of the directions I am seeing are talking about 1 liter starters. However, I brew 10 gallon batches so I was wondering if I should be making 2 liter starters instead? If i'm making 2L starters should I use a bigger fan than 80mm? 120mm seems to be the most common size above 80mm, would 120mm be too big? Also what size stir bar should I use for 2L? I saw 1" recommended for 1L starters so should I double it to a 2" stir bar? Thanks.

I use the stir plate from this thread https://www.homebrewtalk.com/f51/my-stirplate-cheap-easy-build-86252/ and have no problem with starters of 2 or 3 liters.

If you want to make larger starters, you can use gallon glass jugs instead of flasks. I have six stir plates and use jugs for all of them. Some people have problems with the stir bar being thrown since the bottoms are usually domed, but if you get your magnet heights adjusted right and use a stir bar with a pivot ring, you shouldn't have any problems. Jugs are a lot cheaper than a 3 or 4 liter flask.

I have a 2l flask on my DIY stir plate with a 1" stir bar.

It works just fine, and I've made a 1/5l starter with it.

Posted myne here: https://www.homebrewtalk.com/f51/glock-box-320824/#post4418241

BBL_Brewer said:

If you want to make larger starters, you can use gallon glass jugs instead of flasks. I have six stir plates and use jugs for all of them. Some people have problems with the stir bar being thrown since the bottoms are usually domed, but if you get your magnet heights adjusted right and use a stir bar with a pivot ring, you shouldn't have any problems. Jugs are a lot cheaper than a 3 or 4 liter flask.

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Let me holler at you on this one - because this is exactly what I'm struggling with. I have a little fan off amazon as suggested by another man on here. I have glued magnets to this thing that move my 1" stir bar and lock onto it when the unit is still. But, once I get the fan going on lowest setting, the bar (with a pivot ring) either rattles and doesn't spin or it flies off center to the side.

I cant get it working. What do you mean by magnet height? I moved the magnets up away from the fan by separating them with a plastic (empty) tea candle holder. Still no love.

Anybody have issue or concerns about me using those little uber-strong Bucky ball magnets IN the starter? They're metal, so I feel like I could easily sterilize and clean them by boiling them or soaking in sanitizer. I'm just a little nervous about having little metal balls, that certainly look shiny and stainless, being in the yeast starter spinning their balls off.

davepeds said:

Let me holler at you on this one - because this is exactly what I'm struggling with. I have a little fan off amazon as suggested by another man on here. I have glued magnets to this thing that move my 1" stir bar and lock onto it when the unit is still. But, once I get the fan going on lowest setting, the bar (with a pivot ring) either rattles and doesn't spin or it flies off center to the side.

I cant get it working. What do you mean by magnet height? I moved the magnets up away from the fan by separating them with a plastic (empty) tea candle holder. Still no love.

Anybody have issue or concerns about me using those little uber-strong Bucky ball magnets IN the starter? They're metal, so I feel like I could easily sterilize and clean them by boiling them or soaking in sanitizer. I'm just a little nervous about having little metal balls, that certainly look shiny and stainless, being in the yeast starter spinning their balls off.

Click to expand...

What I mean by magnet height, is how close the magnet is to the bottom of the container. Since the magnet is glued to the fan (same as in my case) I guess that really means you have to adjust the position of the fan. I had to play around with mine to get the magnets in the perfect spot. I mounted my fans on bolts so that I could easily adjust them until I found the sweet spot. That was almost three years ago and I haven't had to make any more adjustments since.

A 2L starter for a 10 gallon batch sounds a little low. I brew 10 gallon batches and use Mr Maltys iPhone app to calculate the starter volume, and on the last batch of AHS Blue Moon the app calculated a starter batch of 4 billion cells need. Next there is a book titled yeast and in it there is a recommended yeast starter chart http://multimedia.billybrew.com.s3.amazonaws.com/stepping-up-yeast-starter-table-large.jpg, using this chart I did a 4 liter starter with 2 vials of white labs in a gallon jug on the stir plate for 24 hours and then cold crashed the starter. I decanted the liquid and filled the jug with the cooled wort, put it back on the stir plate for a few minutes to stir up the sleeping yeast and pitched the whole thing into the 9 gallons of cooled/Oxygenated wort, 48 hours later it was had almost fermented out.

This is the same process I use each time I brew no matter what the volume is and my DIY stir plate has been able to handle all of the starters.

I tend to use this calc. Its nice for stepped starters.

http://www.yeastcalc.com/

It says that for 10 gal of 1.060 wort youre going to need 418 Billion cells, a two liter starter on a stir plate will get you at a max with day one fresh yeast 310 billion cells. If youre doing 10 gal batches I second the gallon jug idea if you want to save money. I went that route at first because a gallon of carlo rossi wine in a glass jug was 8 bucks at my local grocery store. I got a glass jug and my friends drunk fir 8 bucks..not a bad deal. That worked for a while but after a while I wanted to be able to heat it on the stove and then transfer the container directly to an ice bath to chill it.. so borosilicate glass i went. Luckily my LHBS has 5L erlenmeyer flasks for $35 bucks.

Now to stir that sucker my little 12v pc fan made into a stir plate wasnt gonna cut it. It would throw the magnet before I could get it spinning and on the rare occasion it didnt throw the mag it just couldnt spin the starter wort fast enough to make a vortex.

So I upped the ante. I bought a 120V muffin fan on ebay (~$15 shipped), ceiling fan speed control from HD (~$10), some strong rare earth magnets from an online retailer (~$5 shipped), cannibalized an extension cord I had, and built the box out of some old scrap wood. Now that stir plate with a 1in stir bar with a pivoting ring with throw the starter wort in my 5l flask like nobodys business.. im pretty sure I could put a large vortex in my carboy if i ever felt the need:rockin: