Stir plate vortex?

So I've been working all day on a computer fan stir plate. I harvested a few magnets and fans and finally got something put together that's actually spinning.

It's a very low vortex though, I'm only testing it on 400ml of water with a shelf pin as the stir bar(one of those metal bars that you use on adjustable bookcase shelving) and the vortex is only about an 3/4 to an inch deep. Is it pulling in enough oxygen to be worth while on a starter? I'm running on high @ 6.8volts. Its all my current supply puts out.

any help would be appreciated.

All you have to do is turn the liquid over. Get yourself a good Teflon coated stir bar and you will be pleased with the results.

Agree. A quarter-sized dimple in the top of the liquid is all you need. An actual vortex is completely overkill, and honestly I think may have negative effects on growth. That last part is speculation only, YMMV.

I think you need to test it on the actual amount of liquid you are going to build your starter with because obviously the more water you have, the more work its going to take to move it around. A 1000 or 1500 ml. of liquid is a big difference than 400 ml. Also, once you have yeast in there, which increases the thickness, it slows down the swirling. Lastly, as krausen builds on top, you won't even see a vortex. The only way to know the bar is spinning, is to listen for the stir bar or to closely watch for particle movement through the glass.
The power you currently have might be enough but these other factors are going to reduce the effects you are currently seeing.
I have one of the stir plates from bigbeavk and I had to run it at 700 rpm to get good movement in a 1600 ml. starter I made last week. With 2" of krausen on top, it seemed it wasn't moving enough at lower speeds.

I'll see if I can throw a different wall wort on up the voltage a bit. I have a 9 volt and 12 volt.. I have a pot on it as well.. that thing seems to take a lot of heat.. anyone heatsink there pot to help dissipate the heat??

cscade said:

Agree. A quarter-sized dimple in the top of the liquid is all you need. An actual vortex is completely overkill.

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there is no reason to beat your yeast. just need enough to keep it in suspension.

Okay, I got a working result. It spins two liters but hardly makes a vortex; It's maybe 12mm wide and the depth is 8-10mm. The "liquid" was highly concentrated sugar water, was trying to represent a start substance with higher SG. Will this work?

I had troubles with the pot getting extremely hot (around 120) after about 20 mins of running. So instead of having the the middle termial as the feed I wired the 1st terminal as + in the second terminal is piggy backed to 3rd terminal, third terminal is + out to fan. The fan - is wired directly to the source -. Using a 25ohm 3watt pot with a 6v source I'm getting very little variance. I'm not very happy with that, I'd like to be a wider range of speed, so I could increase the voltage up to around 9volts. Any suggestions? A different pot?

Check out Mr.Malty.com, it has great info on yeast and starters.

The fan is 12v 200ma if that helps with anyone sharing some insight!

Problem Solved, Thanks for all the input! I broke open another hardrive and doubled up the magnet stack i was using and upped the voltage to 12 volts. I'm now pulling a vortex on 2Liters to about the stir bar! Now I just need a legit stir bar, and Erlenmeyer flask! Very excited to do my first starter on my 60min IPA clone.

steber said:

Problem Solved, Thanks for all the input! I broke open another hardrive and doubled up the magnet stack i was using and upped the voltage to 12 volts. I'm now pulling a vortex on 2Liters to about the stir bar! Now I just need a legit stir bar, and Erlenmeyer flask! Very excited to do my first starter on my 60min IPA clone.

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What part of the above posts didn't you read? You are in complete overkill. All you want to do is keep yeast in suspension. A vortex of any size is not necessary.

iaefebs said:

What part of the above posts didn't you read? You are in complete overkill. All you want to do is keep yeast in suspension. A vortex of any size is not necessary.

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I get that I'm in overkill, the full vortex is only high. The end result came out of a necessary change to the wiring because the way I had the potentiometer wired in was causing it to reach temps higher than my mash temperature! I don't plan to run a full vortex on my starters, but I want to know that If the viscosity of the liquid I'm stirring increases, as it will with the yeast slurry, That I will be able to make sure that my bar doesn't get thrown, or stop spinning.
As well as making sure that I'm getting enough of a spin to insure I am dispiriting the co2 and increasing the gas exchange for oxygen.

Further more, as to a vortex of any size not being necessary, neither is a stir plate, nor a starter. But things like this help, from a chemistry stand point the vortex will pull in oxygen at a faster rate as the water is being folded over faster which we all know beasties love their oxygen!