Multiple generations in AG sour mash

[japsinok]

I am about to complete my first AG mash, a 5 gal mash using a 9lb:1lb:1lb ratio of cracked corn:rolled rye:rolled barley. The mash ended up at OG=1.070 in 4 gals and very sweet, which to my math ended up as a 77% conversion before bringing vol to 5gal. I'm fermenting on the grains and it is nearly complete after 3 days. The SG is now at 1.002 (bubbling about once per second) and no longer has any sweetness. I plan to strip on Christmas Eve day and set up the next generation to start a sour mash run. I plan to double distill enough hearts from enough generations to fill a 5 gal barrel that awaits, using a 5 gal alembic pot still that I have been using now for 2 years. I have made lots of UJSSM so I'm very familiar with using backset to dissolve the sugar, cooling the wash to <90F and re-filling the fermenter where it always returns to bubbling within an hour or two. So, with UJSSM, the entire process through numerous generations requires pitching only once. BTW, I have used Danstar Nottingham Ale yeast in the past but for this AG mash I have switched to Redstar DADY. Now, to the question...While I will use backset in the new grain mash to lower pH and aid the starch extraction/conversion (I use alpha-amylase and AG-300L to convert the starch), I am unsure of how or whether I can easily continue to use the yeast culture in the fermenter, or is it easier/better to repitch fresh yeast. My understanding is DADY is a top fermenter so is there are recommended process to recover from the top layer, or is it best to strain the wort and transfer some amount of the spent grains with yeast to the new ferment? I would like to go multiple generations if possible to see if the yeast character changes across generations as is suggested.

Any thoughts/opinions on how best to reinoculate the next mash, or if it makes any difference. Or is it best to repitch a new starter?

Thanks
just another pot stiller

[still_stirrin]

...Any thoughts/opinions on how best to reinoculate the next mash, or if it makes any difference. Or is it best to repitch a new starter?

Yeast isn't expensive...pitch a fresh starter for a healthy fermentation. It'll reduce the liklihood of off flavors and degenerative byproducts. Since you know how to make a starter, I urge you to go that route. You'll be happier with the product in the end.
ss

[japsinok]

Thanks SS,

That's what I was wanting to know. I bought a pound of DADY and pitched a 10gm starter. Probably could get by with less but that worked really well and as you say, it's cheap. And it'll be less trouble as well.

Many thanks,
japs

[blizzstill]

Bringing up an old thread. From what I understand if I want to go down the AG route for my sour mash, I need to do a first AG mash, distill it. Then, I use backset from my first run (mash #1) for my mash #2 in addition to the mash water?

I never re-use some of the old corn like in UJSSM ?

Thanks!

[DuckofDeath]

Yeah, here is what I do. After I have mashed my grain. I add the water to bring the OG to where I want. So say I have two gallons held back. I will add backset stillage to bring the PH down to what I want. Then use water to finish if needed.