Figuring Out Starter Size Needed

[rodwha]

I have saved used glass jars to save my yeast in. They are of sorts of diameters and lengths making it about impossible to measure the contents.

MrMalty shows slurry in mL. How would one guestimate their volume?

What I had always done was just make a 1 qt starter with 1/4 lb of DME and call it good enough. It seemed to work well enough, but I'd like to be a little more precise or at least know a little better what it is I'll be starting with. A little short or over doesn't concern me, but with higher gravity beers I could be way under pitching.

 

[runkelia]

I think I use 100 grams DME per liter

 

[rodwha]

I'm thinking I ought to fill them up little by little and etch the glass for a rough idea while they are empty.

 

[GotDrunkThenLost]

I've had the same problems after trying to reuse the remains of a too large starter, my starter making process now involves the unused starter going into my recently boiled jug for my stick blender which has markings every 50ml. That then goes in the fridge overnight to see an approximation of where the yeast settles out to in there, this is then transferred into my recently boiled glass jar with the strain and approximate volume written on.

I err on the side of lower volumes just to be on the safe side.

 

[freisste]

Not sure this is smart, but it is my process:

1. Make starter larger than necessary by an easy fraction (for example, if I need 150BB cells, I'll use yeastcalculator.com to size a starter to make 200BB).

2. Once finished, out it in the fridge to settle.

3. Decant liquid.

4. Assuming I have 33% more than I need (and knowing my 2L flask has a mass of 646g), I know roughly the number of cells for the given mass of liquid/slurry.

5. Pour 1/4 by weight into a sanitized jar to be saved in the fridge.

6. Use remainder (still in the flask) to pitch.

After these steps, I have a pretty good estimate of the number of cells I have. I have not yet used the yeast from the oversized starter, so I don't know how large a starter (or stepped starter) it will take, but I usually end up with 60-70BB cells extra. I will likely have to use a stepped starter to get back to a reasonable yeast colony because I'll probably only have 30-40BB cells by the time I try to use it.

I'm not sure, but I imagine this is more accurate than trying to determine the number of ml of slurry in a jar, even if it was scientifically graduated. Anyone know of a reason this is inaccurate?