When to use an "acid rest"?

[john_galt]

I am a little confused on when to actually use a ~92 degree acid rest.....I had been on most batches for a while, but now I am trying to streamline my all grain brewing practices......When is an "acid rest" needed? And what "exactly" is it? Best procedure to have an "acid rest"? Thanks Everyone.

[Azorean Brewer]

John,

From what I have read, acid rest serves two purposes, one is to rehydrate the grist, and the second can be and should be when you want to lower the pH of your water when your water is high in alkalinity.

Utilizing an acid rest can lower the pH of your liquor up to .8 IE: 6.5 normal pH, and after acid rest 6.0 - 5.7 pH.

I typically use 1-2 teaspoons of gypsum, and conduct a protien rest of 122F for 30 minutes and don't worry about an acid rest. Then raise the temp to 146F for 15, and bring the grist up to 154-158F for a final 30-45 minutes. I know this is not the a scientific explantion, but it is as I understand it.

The protien rest (of 122F) gives the yeast addition nutrients that are missed in a single infussion mash.

With todays grains being so well modified, the mash times really do not have to go beyond 60 minutes. I will typically use no more than 90 minutes total with a single or step mash schedule, anything more is just wasted time.

Regards,

Paul.