Stir bar or fleas

[Wonkydonkey]

I use to work for a penicillin manufacturer in a quality lab, and we called the stir bars "fleas" . Anyhow I know you can get all sizes of fleas as well as a few different shapes.
From what I remember. Some are better at doing different things, as well as the speed they spin at. That is stirring in or stirring out O2 or Co2 which is dependant on the size and shape of the flea and volume being stirred, even the shape of the flask has an effect.
It was a long time ago so things are a bit fuzzy now.

I now use a triangular flea, that I found in a draw. ( how it got there is fuzzy now) It's been there for yrs and it's now out of retirement.

My question is what size and shapes of fleas do you guys use.
What speed do you are you spinning, slow, medium, fast or turbo fast.
how do you rate them, good or not so good.
has anyone else used a triangular one.

[Belter]

I don't know what you're on about whatsoever but I use a triangular stir bir. It's awesome. Way better that my round ones which clatter a little

[tourer]

I don't know what you're on about whatsoever but I use a triangular stir bir. It's awesome. Way better that my round ones which clatter a little

I'm glad you said that Belter i thought it was just mine that rattled (the round bar shape)

[richc]

So where is a good place to get triangular ones?

[pads72]

I just bought some from http://www.camlab.co.uk which I thought were cheap (91p ex-vat not incl p&p). The pivot bar ones clatter, which I assume is due to a slight misalignment of the magnets, but the 25mm triangular stir bar is silent and works a dream, see my build post

viewtopic.php?f=6&t=64928

[Belter]

I got mine from king scientific

[Wonkydonkey]

Hi guys,, thanks belter.... Yes I think the triangular shape works a whole lot better for stirring in 02 ( oxygen ) which the yeast love for reproduction. it's the shape that really stirs the whole lot up, where as the round bar type just stirs and if you get it at the right speed it can give a vortex in the liquid but it's rounded shape does not really mix in the air or O2 what ever you want to call it.. I'm sorry for being a bit scientific in my first post.
and yes I did see them on chemlab.co.uk.

Tourer. Yes the round one rattle more than a rattle snake. I use to have 40 flasks at a time stirring my penacillin solutions, it was hell being within 20 yards. The faster they spin the more noise they make.
So for what ever they cost, I think it's worth a try if your looking for another bar as a spare. I think you will use it more than the round ones

[Wonkydonkey]

Pads72
it's not the miss alignment, from what I remember.
I think it's the speed of liquid being stirred making it rattle
Well wobble up and down really.

[tourer]

I think i've found a solution to the stir bar rattle. Money wasn't the issue just another problem to be solved. I was going to buy some bars local to me when i had a thought. The round bars have a rib around the centre and the magnet on the bar and it tends to bend to the magnetic field as it turns around so the positive side of the bar will move down to the negative and vica versa on the stirer underneath so by shaving off the rib around the bar (make nice and smooth) the magnet wont bounce up and down. It works i'd say voila but i can't spell it, so if your watching the pennies try that.
Good luck