Stir Bar Problems

I have a homemade stir plate with 2 in. magnets connected to the fan. I had two 2 in. magnets that I used as stir bars, but one cracked in half and on the other one the silver coating is chipping away (worrying me). I ordered a stir bar from my LHBS, but it is a small pill sized thing. It won't spin the water of any amount.

Will this one work somehow or do I need to buy another longer one? If I need a new one where is a good place to purchase on online?

I'm usually using a ~1.5" long stirbar in my flasks (2L and 3L) with great results. I'm also using the Hanna 190M stirplate. Not sure how well yours is working, but try testing it with a flask full of water to see how the bar spins.

Unfortunately, my 2L flask won't spin with the new pill sized stir bar with any amount of water.

Stir bars come in many different sizes. You can actually pick one that this is too large if you aren't careful. The teeny tiny ones are for lab use in very small flasks, and as you have discovered, don't do so well in the larger flasks. I use a 3L flask with a 1.5L starter and use a 1.5" bar that works very well. I also have a 2" bar that is really too large (it wants to spin off the magnet periodically). I would suggest buying 2 or 3 of the 1.5" long bars (I like the octagonal ones, but it doesn't really matter) and they will work fine for you.

Be sure to get the Teflon coated ones. These won't chip and can be boiled without a problem. Try McMaster-Carr at this link: http://www.mcmaster.com/#stir-bars/=k8vfvp

If you have an Amazon Prime account, you can get them from Amazon too. After you factor in shipping, especially with the Prime account, Amazon is a viable option. I would also go with the 5/16" diameter, not the larger ones.