Partial Mashes and water chemistry

[soupfist]

So for the past few batches, I've moved up from partial boil/extract brewing to partial boil/partial mashes of about 3-4 lbs. worth of grain.

So far I've created an absolutely horrible oatmeal stout and an Irish Red Ale that started out OK but I'm trying to drink quickly because each bottle has a stronger phenol bite than the previous one (it's sinking fast...). Also just bottled a brown ale that seems a little bit on the tannin-y side, and a vienna lager in a primary that I'm crossing my fingers on...

Then I started reading about water chemistry and took a look at my water vs. what I was trying to brew. Realized my mash PH was quite likely going through the roof because the local water has really low alkalinity and everything I've been brewing has been on the dark end.

So, obviously there are many calculators to help correct the mash pH. All the ones I have seen start with the approximate SRM you're trying to brew and adding salts to raise or lower alkalinity. But it occurred to me, if all I'm doing is mashing 4 lbs of grain in 2 gallons of water, sparging, and then adding extract during the boil, wouldn't I have to adjust to the SRM of the wort being mashed? In other words, calculating the SRM based on the grains being mashed in 2 gallons of water?

Example: I'm looking at a recipe for the vienna lager I just brewed. It's SRM 11 and the recipe called for 2 lbs Vienna, 1 lb Pilsner, 4 oz Melanoidan and 2 oz De-husked Carafa III, with 3.3 lbs of light DME backing it up. If I remove the DME and change the water volume to 2 gallons in my brew calculator, the estimated SRM of the mashed wort becomes SRM 19. Would I be right to plug that value into the alkalinity calculator instead of SRM 11?

Am I overthinking this? I tend to do that...

 

[Yooper]

Actually, forget that you ever heard anyone mention SRM and alkalinity and pH in the same paragraph. Although it's true that highly roasted malts can drop the pH more than lower kilned malts, it's not all that much and color has very little to do with it.

For the next batch, I'd suggest buying some reverse osmosis water and adding a little calcium chloride (see the "water chemistry primer" sticky in the brewing science forum) and see if that fixes your problem. If it does, you know it's your water. I'd also suggest a water report from Ward Labs. It's $16.50 for a water report that will tell you exactly your water composition. It's well worth it, if you plan on brewing for a while.

In my case, I have very alkaline water so I usually buy some RO water from the "water machine" at the store ($1.50 for four gallons) and mix it with my tap water along with a little CaCl2 for perfect brewing water.

 

[Xaphoeous]

I think I'll get my water tested, just for schnitzengiggle. I have brewed 2 batches since moving into the new house, neither of which have been tasted yet. Not sure how the water will affect my beers!

 

[soupfist]

Thanks for the advice. Your sticky also mentions sauermalz, though your post here does not. Is this significant? It doesn't appear to be available locally...