I like the idea of decanting the extra beer off of a starter after letting it sit in the fridge for a couple days. I always cringe when I pitch a starter full of extract beer into a batch. Ideally then, you'd make a small starter just before you brew to invigorate the yeast and get them ready for some big work. I've been pondering how to go about using the beer I'm making for that starter so I'm not dumping a bunch of different beer in with the yeast at pitching time. The one perfect moment would be during the sparge when the runnings hit that 1.040 mark. I was thinking about grabbing a liter or so at that moment and boiling it for 10-15 minutes to use for reinvigorating the yeast. The problem is, I'd usually be ready to pitch maybe two hours later. What would be the minimum amount of time the yeast should sit in that secondary starter? Is two hours enough? We're not really fermenting, we're just letting the yeast soak up some nutrients to bolster their cell membranes. Would it be more detrimental to hold off on pitching for a few hours than making the effort to use the same beer to invigorate the yeast?