Double batch in one fermenter

[rimfire]

On Day One I brew a 5.5 gal extract batch (1.058 OG), oxygenate the wort and pitch double yeast (2 liquid vials of cal ale no starter) into a 14.5 gallon SS conical. On Day Two (within 24 hours) I brew a 5.5 gallon all grain batch (similar gravity) and add it into the same fermenter to make 11 gallons. The first batch doubles as a large yeast starter for the second. I do not oxygenate the second batch (other than incedental during transfer).

Are there any negative issues with making such a large "starter" (5.5 gals at 1.058 OG) on day one - i.e. growing too many yeast cells too fast, stress, oxidation, etc?

If I were to make an even higher gravity wort (i.e. 1.08 imperial stout) would you recommend making a starter for the "starter" (i.e. day 1 make a 2L 1.04 starter, day two pitch starter into oxygenated extract batch, day three fold in the all grain batch).

Thanks

 

[TipsyDragon]

it wont stress the yeast if they are of a variety that can handle "high gravity" brews.

 

[audger]

i dont see anything wrong with doing it that way- with the one exception that you are going to be oxygenating the beer when you mix the partly-fermented, largely oxygen-free beer with the second batch of oxygenated wort. how much of a difference adding oxygen makes at 24 hours after pitching?- i dont know.

and a starter of a starter is not necessary.