mineral ppm increases with boil off?

I have a question about water treatment and how much the ppm from the ions increases with boil off. My question is this....If I need 9 gallons of water for an all grain recipe to end up with 5.25 gallons after mashing/boil....do I treat my water based off the initial 9 gallons to achieve a certain profile or base additions off of the ending water volume of 5.25. I would think if I treated water for 9 gallons to reach desired profile it would increase to much higher than wanted minerals after boil off...am I wrong?

 

You are right. You treat for the ion concentrations in the final desired volume.

 

Nope. You treat your water based on the total pre-boil volumes. As long as you aren't boiling the crap out of the wort and loosing more than about a gallon per hour, the effect of the mineral additions is correct.

Think about this: In the days before brewers understood that they could alter their local water with mineral additions, they used the mineral content they had and they boiled the wort down as desired. They didn't somehow alter their mineral content to fit the final wort volume.

 

Confused then...

I boil off about 1.2 gallons an hour... Regardless of batch size. With my 1 gallon test batches, if I computed for a 2.2 gallon boil, I will have doubled the concentration, where when I do 10.5 gallons, the preboiling is usually 11.7 gallons resulting in a far smaller concentration, a roughly 10% concentration?

Not arguing, just not following the logic.


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Now that I think about it, perhaps a 50% boil off of a small batch might be boiling the crap out of it!


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boiling a gallon off of 9 gallons is entirely different than boiling a gallon off of 2 gallons. For the first I'd say don't sweat it, for the second I'd say it might matter.

Only one way to really find out...brew it both ways and see.

 

You treat the 9 gallons but you don't do it to match a profile. You do it to get the beer you want. When you experiment to determine the proper salt additions you do it under the assumption that your process is the same each time you brew. If you determine an optimal set of salt additions for a system with 10%/hr boil off and move to one where the rate is double that then you should allow for that in your stylistic ion additions but not those done for pH control.

 

Of course. And AJ you and Martin picked up on the mash/boil volume statement. I overlooked that, and mistakenly focused on what appeared to be a massive 40+% boil off rate.

 

So I BIAB and have a 19 gallon pot, but so far have mostly done 5 gallon batches (bought it so that I could do 10 gallon batches).

My boil off is nearly 2 gallons per hour. Would it be okay to decrease my boil-off rate by putting the lid partially on, leaving a crack for DMS to escape (in the case of pilsner)?

Or what about calculating mineral additions I would need assuming I only had a 1 gal/hr boil off rate and then just adding that amount. That way, they would be concentrated at the end volume, but only to the amount they would be had I only had a 1 gal/hr boil off.

I understand it's an experience thing - to know what water profile you want based on taste, but I lack that experience and need somewhere to start.

Would you try decreasing boll off rate if you are me or just add mineral additions that would be needed of my evaporation rate were lower? I'll of course correct for ph. With full volume biab I'm still going to lose a fair amount to grain absorption anyhow.

 

Pro brewing systems limit the evaporation rate to between 5 and 8 percent. That is far different than the typical homebrew system. Partially covering the kettle does help reduce the evaporative losses. If elevated DMS is a concern, I think that uncovering and boiling a little more vigorously for maybe 10 minutes at the end of the boil would do the trick for driving off DMS.

 

I'll usually start off with a hard boil, then reduce the intensity of the boil as I get closer to the end. You could dial back your boil and reduce boil-off that way.

 

I'm wondering if this is perhaps a topic that has a huge effect on some of us, but is rarely discussed.

I brew mostly 2.5 or 3 gallon batches, and evaporate a little more than 1 gal/hr. So I have a boil-off rate of 30-35%. Luckily I'm not heavy-handed with brewing salts as a general rule. But I do wonder if the final profile of my beer is consistently more acidic - for flavor considerations - due to higher post-boil mineral concentration.

Or does it not really work that way?

 

Did a test run. Covered the pot 80-90% with the lid and was lost about 1 gal/ hr.