Depends on what you want...Munich malt seems to not be used very often in German alts, although I really like it in my version. I do a 60 min. mash at 150. Never bothered to check pH because between my water and the dark Munich they always turn out great. But I think your pH target looks good. If you want to go more German, look for the Zum Uerige recipe here in the forum. Here's my American take on an alt, which has won me a lot of awards....http://wiki.homebrewersassociation.org/MilosAlt
Thanks Denny. As mentioned, I developed this after looking the Zum Uerige recipe which I have saved. My thought is that 1 pound of Munich 9L isn't going send this too far out of bounds. The recipe which I have tried 2 or 3 times had about 22% munich so I have backed off considerably. I think I have about 2 oz more caramunich than what I would use for the Zum Uerige recipe on my system.
I applied some of what Martin was thinking from another thread:
"I've brewed at both ends of the malt bill spectrum and I have to say that neither grist is correct. With a very high proportion of Munich malt, the beer is too richly malty. I just brewed the recipe that Denny posted which is at the all Pils end of the spectrum and have to say that its fine, but it needs just a bit of Munich to add to the depth of malt flavor. I'm guessing that about 25% light Munich might meet the depth I expect."
So basically, I am just hoping that the munich will add some malt complexity without being too overpoweringly malty.