fresh all grain wort to step up starter?

[Fritz Eye]

Hi All,
Looking to step up my starter the morning of my brew day. The plan is to make the starter about 3 days in advance. Let it finish out on a stir plate for 2 days and chill in the fridge for another day. On the day of the brew I would like to take the first runnings of the batch sparge, boil 1 liter or so of for about 15 minutes and cool to pitch temps. I would take the initial starter out of the fridge, decant the spent beer off the yeast and then pitch the fresh wort on top. This will sit on the plate for another 4 hours or so, giving it time to wake up and grow a little more.
Is this overkill, most of my beers are around 1.070 and lower. Also I would pitch the new starter wort, trub and all onto the yeast cake. Any issues with that?
As usual,thanks for all your support.
Cheers.

[brewranger]

well i am just starting reading my yeast book, but I would think that your first runnings would be way too high of gravity for a starter. The high gravity will stress the yeast. I would recommend using DME. If you don't have any DME around, I would either dilute the first runnings down to around 1.030 or take last runnings.

[Fritz Eye]

well i am just starting reading my yeast book, but I would think that your first runnings would be way too high of gravity for a starter. The high gravity will stress the yeast. I would recommend using DME. If you don't have any DME around, I would either dilute the first runnings down to around 1.030 or take last runnings.

awesome point about the first runnings having a higher OG. Chalk up another reason to get a refractometer!
Thanks.