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Old 10-09-2009, 02:59 AM   #1
beltbuckle
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Sep 2009
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I had an unfortunate accident last night that destroyed my beloved 5000mL erlenmeyer flask. I'd only used it twice. But one thing that I discovered after I had bought it was that it wasn't big enough, and neither was my labratory-surplus stir plate I had purchased off eBay.

Oops.


You see, I do 10 gallon all-grain batches, and for bigger beers, say 1060+ (which is pretty much 80% what I have been brewing), I'd always wanted to create a starter that had the cell count that followed Mr. Malty (JZ's) or WL or Wyeast's recommendations. What I discovered after I bought my 5000mL flask was that if I wanted to use a single smack pack or vial of yeast to inoculate 10 gallons+ of wort, I couldn't make the required cell count with what I had. Sure, I could make a good starter, but not good enough.

For an example, this Sunday I will be brewing 10 gallons of Dean Larson's Sierra Nevada Celebration Ale clone. It has an OG of around 1064. Running the numbers through Mr. Malty, it says I need about a 7 liter starter if I start from one Wyeast Activator pack. 7000mL? Yep. That's a big ass starter.

So after my flask broke, I decided I would do it right. I looked at larger flasks, but to tell the truth I wasn't that crazy about glass since it was so fragile. I considered HDPE or PETE plastic, but that adds a transfer or starter wort, and another chance for infection. So I went to a local restaurant supply store, and for about $25 I came home with a 12 quart aluminum stock pot and lid. I purchased an aluminum one since I do use a home-made Binford 9000 (120v A/C, 3 amp motor) bigass stir plate, and needed a non-ferrous metal or plastic vessel for the starter to avoid magnetic field issues.




I tested it with water, not sure if it would work or even pull a vortex with such a large amount of liquid. It did. Not a Wizard-of-Oz -Tornado, but a nice little vortex that would surely keep yeast suspended. Good enough.




So I scrubbed it with Oxy-clean, added the 7L of water and 700 grams of DME, and boiled the wort for 20 minutes.




Nice thing I discovered with this setup is that it cools much faster that my old flask. Aluminum is such a good conductor I bet it cooled to pitching temps twice as fast.




It's now on the strir plate, ready to brew on Sunday. I put a SNPA bottle on there to show scale.

 
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Old 10-09-2009, 11:33 AM   #2
lehr
 
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One question are you clicking on the stir plate option on mr malty because I dont see where your getting the 7 liters from. I just made this beer but I did Mike McDoles 1999 recipe 1.074 og and used 2 pks of dry yeast and over a pound of hops.

Pat

 
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Old 10-09-2009, 01:33 PM   #3
Cold_Steel
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Can you give more details about the stir plate?
Do you just place the lid on the pot?
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Old 10-09-2009, 02:39 PM   #4
beltbuckle
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Sep 2009
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Quote:
Originally Posted by lehr View Post
One question are you clicking on the stir plate option on mr malty because I dont see where your getting the 7 liters from. I just made this beer but I did Mike McDoles 1999 recipe 1.074 og and used 2 pks of dry yeast and over a pound of hops.

Pat
If you move the slider bar to only use one vial of liquid yeast, that's the amount of starter it recommends. Obviously you could use more yeast packs and use less starter but at around $6.00 a piece, I'd rather make a bigger starter.

Here's the Mr. Malty screenshot showing what I used. Basically a batch size around 11 gallons, 1 vial, OG of 1064, viability of 85% (yeast production date of 9/22/09), and using the stirplate option. Without a stirplate, it comes up with almost 19 liters of starter!


 
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Old 10-09-2009, 02:57 PM   #5
beltbuckle
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Sep 2009
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Quote:
Originally Posted by Cold_Steel View Post
Can you give more details about the stir plate?
Do you just place the lid on the pot?
The stir plate I just threw together. Made a 13" wood box, I had a 6" a/c fan I pulled from a computer equipment rack. The fan is 1600 RPM which is about right for a stir plate. I cut the blades off of the fan, then I added a dimmer switch which is just used to gradually get the motor up to full speed so it doesn't throw the stir bar. For magnets I use two magnets from hard drives. It's just like most of the other DIY stirplates, just using a larger A/C fan.

A/C motors generally don't like to be speed-controlled by controlling their voltage, but this works just to get it up to full speed. A DC motor would be better and easier to control, but I had the fan for free so the whole thing cost me about $5 for the dimmer at Home Depot.

The pot is just a 12 quart aluminum stock pot. I keep the lid on while boiling, cooling, and stirring - except to pitch the yeast. It obviously is not air-tight, but I would liken it to putting foil over the mouth of a flask. Not an airtight seal, but keeps the bugs from falling in.

 
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Old 10-09-2009, 03:49 PM   #6
lehr
 
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Thats strange I just put the same thing in mr malty and it said 5.8 liter and 98 % viability.

 
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Old 10-09-2009, 04:05 PM   #7
Clayton
 
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hum i guess i dont get it?
why not just decant off the beer in the starter?
i have a 1000ml flask and when i need a bunch of yeast i put it on the stirplat and then cold crash, decant ,and add more wort till i get the amount of yeast i need.
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Old 10-09-2009, 04:14 PM   #8
beltbuckle
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Sep 2009
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Quote:
Originally Posted by lehr View Post
Thats strange I just put the same thing in mr malty and it said 5.8 liter and 98 % viability.
Check that viability. I had a calculated viability of 85% since my yeast production date was 9/22. Remember every day that goes by some yeast cells die in the package.

 
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Old 10-09-2009, 04:16 PM   #9
beltbuckle
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Sep 2009
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Quote:
Originally Posted by Clayton View Post
hum i guess i dont get it?
why not just decant off the beer in the starter?
i have a 1000ml flask and when i need a bunch of yeast i put it on the stirplat and then cold crash, decant ,and add more wort till i get the amount of yeast i need.
This doesn't work. Yeast are "smart" in that they will only multiply to reach a certain cell density in a given volume of wort. You can't just "rinse and repeat" as many times as you need to get your cell count up, you will always hit a limit of around 100 billion cells in a one liter flask.

 
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Old 10-09-2009, 05:13 PM   #10
Schnitzengiggle
 
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Quote:
Originally Posted by beltbuckle View Post
The stir plate I just threw together. Made a 13" wood box, I had a 6" a/c fan I pulled from a computer equipment rack. The fan is 1600 RPM which is about right for a stir plate. I cut the blades off of the fan, then I added a dimmer switch which is just used to gradually get the motor up to full speed so it doesn't throw the stir bar. For magnets I use two magnets from hard drives. It's just like most of the other DIY stirplates, just using a larger A/C fan.

A/C motors generally don't like to be speed-controlled by controlling their voltage, but this works just to get it up to full speed. A DC motor would be better and easier to control, but I had the fan for free so the whole thing cost me about $5 for the dimmer at Home Depot.

The pot is just a 12 quart aluminum stock pot. I keep the lid on while boiling, cooling, and stirring - except to pitch the yeast. It obviously is not air-tight, but I would liken it to putting foil over the mouth of a flask. Not an airtight seal, but keeps the bugs from falling in.
Wow, I plan on making 1 gallon starters on my stirplate for my 10 gallon AG batches, now I'm wondering if my DIY stirplate will even work with my gallon jugs?

Do you know of a source for the fan you used or a similar D/C fan?

I may need to make a larger stirplate, I vote for a DIY thread on your stirplate!
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