10 Gallon Batch, 2 carboys and getting 1 big starter to split evenly

[hylander0]

So when it comes to getting the best results out of your beer yeast pitch rates are vital. This area is my next stop on improving my craft.
I do 10 gallon batches but like to split between 2 carboy/buckets because I do not care move around 10 gallons around. I start with one vial of yeast, calculated amount of DME/water and began building up my yeast count prior to the brew day.

At the moment this is something I am trying to improve upon, getting the right pitch count and splitting it evenly. Before someone says RDWHAHB I want to get a simple solution to a common problem so I can do just that.

Currently, I take my starter (1 gallon jug) built up large enough for the 10 gallon batch, decant most liquid, swirl it as vigorously as I can and eye ball it, splitting as evenly as possible. But it is impossible because usually the bottom half of the starter is more concentrated then the top half, especially with highly flocculate yeast.

Since I have been taking notice of this practice I also notice one batch’s FG is always serval points higher than the other, clearly under attenuation. This is something I shouldn’t just say RDWHAHB can live with it.

So here are some solutions I have heard:

1. Split in half or ¼ back and forth between vessels by eyeballing it
   
   - Currently doing and doesn’t work. If it does work for you then is it because I suck at it and shouldn’t be doing it.​
2. Take some wort during the boil, cool and add it to the starter to arose the yeast then eyeball splitting it is more consistent by liquid volume.
   
   - Still eyeball method, solves the problem of flocculation/clumping but still very prone to error​
3. Add your starter to your chilled kettle and split then.
   
   - I think is worse the eyeballing it. Because the yeast could easily fall to the bottom into the trub and never make it into the fermenter. Resulting in under pitching both batches.​
4. Get 2 stir plates, 2 starter vessels/flasks, split the DME volume and split the vial of yeast.
   
   - My guess is when you eyeball splitting the vial across two starters inoculation rates come into play. The lower the rate, the more yeast growth you will get vs higher will result in lower growth rates.
   - This is probably the way to go but more equipment to clean which I always try to avoid.
   ​

I would think option 4 is the best but I am interested to hear of other ideas and methods everyone else has tried, successful or not.

 

[CU_tony]

I would say #4 sounds the most reasonable, though for a more scientific process, you may consider stepping up the vial in one flask, then splitting that between two flasks to step up again.
I kinda feel like it will be easier to evenly split 1L of starter than a tiny vial.

 

[hylander0]

I kinda feel like it will be easier to evenly split 1L of starter than a tiny vial.

That is a great point.

 

[positronic]

Pour decanted starter into a sanitized beaker so you can easily measure how much goes into each fermenter.