Anyone try something like this out for yeast starters? https://www.amazon.com/gp/aw/d/B07CPWVL6P/ref=sspa_mw_detail_1?ie=UTF8&psc=1 5L expandable food grade bags. Obviously you couldn’t do stir plate but you could shake it up and hit it with O2 stone a few times in 24 hrs.
The Aussies use those things for fermenting the entire batch right? I've never tried it but if it works for them, it would probably work for a starter too.
Here's a question, why do you even need a stir plate? Who's making a big enough starter that you need one? Yeast know what they're doing. Just my two cents.
For me it's not only about starter size, but also about time. Stir plates are faster. But regarding both time and size, I recently made a 4.4 quart starter (with two packs of yeast) with a stir plate. To target about the same amount of cells without a stir plate (i.e. with "periodic shaking"), I would have needed to do a two step starter (about 1.6 quarts and 3 quarts), so not too much more total wort, but more time. Or, I could have gone with a single step periodic shaking starter of about 6.6 qts, which probably would have taken even longer, due to a very low (possibly too low) inoculation rate.
