I have brewed a few higher gravity beers now. I only have a 2,000L flask. So, I sometimes have to step them up another time. On the second starter they foam over and blow off the sponge. It looks like I'm losing a decent amount of yeast here. Now I don't know if I really grew my intended amount of yeast. I usually do starters of about 1500L for this flask each time. Am I doing something wrong or do I just need to invest in a bigger flask?
The Erlenmeyer will do this a lot if fluid level is anywhere close to the top. If I need to step up 2x I decant the spent wort, retaining the yeast and add new wort so that my fluid level stays below 1200ml, but even then you have to watch it.
Are you using a stir plate? The the vortex created by the stir plate will usually keep the krausen in check. If you are using a stir plate then I'd say to invest in a larger flask and/or try using fermcap to control the foaming.
Had my first blow off... maybe I should start using fermcap in my starters. Left this morning with a little trickle coming out from under the foil. 4 hours later:
It took the foil cap right off the top! That's 1600ml of 001 ~20 hours in.
I usually get a significant blowoff with all of my starters. I really don't worry about it. I put a piece of wax paper on top of the stir plate and put the stir plate in a plastic tray to catch everything.
That's what I did, too, but I found that it was losing yeast through the blow off which sort of defeats what I am trying to accomplish. I think I just have to keep it below 1500ml.
I usually get a significant blowoff with all of my starters. I really don't worry about it. I put a piece of wax paper on top of the stir plate and put the stir plate in a plastic tray to catch everything.
genius. woke up today with blowoff crud all over my stir plate. fermcap next time and wax paper. noted