[Kaiser]

I consider the optimal pH mash pH to be between 5.2 and 5.6.

But here you are talking about an imagined mash temperature, pH, right? 
Do you mean a measured pH of 5.4 - 5.8, at r.t.?

no, I'm talking about a mash pH target of 5.2-5.6 when measured in a room
temperature sample. I don't really care what the actual pH at mash temperatures will be like.

Kai

[malzig]

I consider the optimal pH mash pH to be between 5.2 and 5.6.

But here you are talking about an imagined mash temperature, pH, right? 
Do you mean a measured pH of 5.4 - 5.8, at r.t.?

no, I'm talking about a mash pH target of 5.2-5.6 when measured in a room
temperature sample. I don't really care what the actual pH at mash temperatures will be like.

Kai

5.2 just seemed low for an r.t. mash pH.  I've never gone that low.

[mabrungard]

I agree with Malzig that a room temperature mash pH of 5.2 seems kind of low.  When I've made water adjustment mistakes and ended up with mash pH in that range, the resulting beer is well attenuated and thinner. 

I don't think that I would go lower than about 5.4 for a room temperature mash pH. 

[Kaiser]

I agree with Malzig that a room temperature mash pH of 5.2 seems kind of low.  When I've made water adjustment mistakes and ended up with mash pH in that range, the resulting beer is well attenuated and thinner. 

I don't think that I would go lower than about 5.4 for a room temperature mash pH. 

the 5.2 number comes from Kunze. Narziss/Back suggest 5.4 as the lower limit. I too agree that 5.2 is a bit too low,  but I have used it with sucess.

These days I oftentimes employ combined mash and wort acidification where I adjust the mash pH to 5.4-5.5 and adjust the kettle-full wort pH to 5.3-5.4.

Kai