Double Starter

I'm brewing up two batches over the next two weeks. Both recipes call for the same yeast. If I doubled my normal starter would splitting it in half work in both batches? I make them with 3oz of dme in 1qt water and they normally come out to about 1.046. If I just doubled everything wouldn't it double the yeast count as well?
The 1st is an IPA with a starting gravity of 1.055 the other is a stout with 1.063.

Thanks for looking...cheers!

My first question is how big is your starter vessel? You could probably get by with splitting a full 2L starter, but if it were me I would use a 5L to make sure the cell counts get high enough. From you equation, you are making just under a 1L starter which if doubled would get you in the right ballpark for making a 1.035~ starter. However, doubling the volume does not equal double the cell count. Looking at Mr. Malty yeast calculator, it looks like you need 2 vials/packs of liquid yeast into a 1.65L starter on a stirplate to generate the calculated cell count of 417 billion cells needed to inoculate 10 gallons of wort. If you have a 5L flask you could get by with 1 vial/pack on a stirplate... play with your options at http://www.mrmalty.com/calc/calc.html to find the scenario that fits you bet.

Good luck!

As RiverCityBrewer stated, you need to have a vessel large enough to reach a certain cell count. Think of it as squeezing as many people into an elevator or phone booth that you can, only so many will fit before space runs out. The same is true with yeast, they can only occupy a certain amount of space in your starter vessel before they run out of room to continue to grow and reproduce.

I have had success making starters for 10 gallon batches in a 1 gallon growler, but it can get messy:


Stepping your starter-up is one way to get around using more yeast packs or vials, but you definitely need to plan your starter a few days in advance. If I'm brewing on Saturday or Sunday, I'll usually get a starter going Tuesday night or Wednesday morning. It gives me the opportunity to let the first 2qts ferment to high kraeusen usually ~18-24 hours, then I pitch my 2qt step-up for another ~24-36 or until completely fermented out. Afterwards it is into the fridge for at least 24 hours, but I like to let it chill for 36-48 hours. Decant and pitch on brew day.

I have had lag time of as little as 3 hours.

MrMalty.com is definitely one of the best sources for all things starter related, not only the cool calculator, but Jamil has some great tips on how to make a starter properly.

I am going to be purchasing a 5L flask whenever I can find one on sale. Unless anyone out there has too many and would like to donate one!

Very cool info, thank you. I didn't know if my growler would cut it or not and from looking above it may prove a bit messy lol. I suppose I could look into a 5l starter vessel too. It may save me some mess in the future.
I had thought about making a 1L starter, letting it hit high krausen, then split it in half after a good shake. After that I'd add a little more wort to each starter.
I will definitely look at Mr Malty. I forgot about the site unfortunately.