Does the speed of the stirplate cause a significant impact on cell growth when making a starter? I ask because I recently found out I could use a one gallon flat bottom glass jug on my stirplate. It works but the stir bar falls out of center when the speed is past 75%. I guess the tangential momentum unseats it since the glass jug is not perfectly flat on the bottom. Thoughts?
You should be fine. I only try to go fast enough until I start to see a whirlpool in the center. You don’t have to go super fast.
It just has to be moving. How fast has no impact really. Its about bringing the liquid continually to the surface, while also creating enough agitation that the solution is degassing as well the any residual CO2 from the cellular respiration.
I agree with warchez. I haven't bothered with the huge whirlpool for years, primarily because I don't want the foam to pour out overnight. As long as the yeast is circulating, that should be enough. It might take a couple of hours longer, but so what? I'd rather not deal with the potential mess, and risk of contamination when the protective foil lifts off.
Ok good deal. Well in that case... a brewer on a budget may find that a few of these 1 gallon jugs (<$10 each) may be a good alternative to going in on a 5L erlenmeyer flask.
For anyone who may be interested, where did you get the jugs? I went all in on a 5L flask because when I looked for suitable 1+ gallon glass alternatives, I didn’t find anything that cost less than the flask at ~$40. Might be nice to have a backup for when I inevitably break this flask.
@Ten_SeventySix_Brewhouse Amazon (sorry LHBS). With Prime free shipping I got a pack of 4 jugs for $23.
I think that most 1 gallon jugs have a slightly concave bottom. It is possible to 'balance' a stir stick on the top of the curved surface, but it is tricky.
The stir plate does not need to be moving very fast. If you see an incubator in the lab it is just shaking back and forth, no vortex. Curved bottom vessels are difficult to use on a stirplate. I guess if you have a small stir bar that helps. (insert joke here) If you do get a flask DO NOT boil the wort on an electric coil type stove. It will fuck up the flask and break it. Maybe not the first time but it will. Ask how I know. Before I had a stir plate and did the intermittent swirl thing I had a starter going. Went to swirl it and the damn thing broke, spewing yeast culture as far as the eye could see in the kitchen. Almost as bad as mopping the ceiling after a airlock clog in a bucket. Almost.
