Beersmith adds baking soda to mash, ph to high?

[troyp42]

Hi guys, Ive been using the water tools in Beersmith but what I dont get is it tells me to add baking soda to the mash, but then my PH is too high and I have to use lactic acid to reduce it.

Todays beer is shown below. 5 mins after mash in my ph was 5.9 so I added 8mls of lactic to 20 litres water. Its as still a bit high 5 mins later so I added another 4 mls. I should have waited longer as now my mash is 5.12, but from what Ive read thats still ok. However I dont get why beer smith says to add baking soda if Im only going to have to lower the ph again with lactic. Should I just start laving the Baking soda out?

 

[RPh_Guy]

What was the pH later?

 

[troyp42]

It stayed around 5.1 didnt drop anymore.

 

[Vale71]

However I dont get why beer smith says to add baking soda if Im only going to have to lower the ph again with lactic.

Do you have a full water report for your brewing water and did you enter all the values correctly in Beersmith?

 

[troyp42]

Do you have a full water report for your brewing water and did you enter all the values correctly in Beersmith?

Yeah I do and I entered it into Beersmith awhile ago. Im not sure how accurate it is but someone here in Melbourne posted it on AHB and from what Ive read its accurate enough. Problem is depending on where you live in Melbourne your water is sourced from a different dam and in some cases from the desal plant. I did just update the PH as the report said it was around 7.2 but I checked it today and it was 8.4.

Heres the water profile and the adjusted values below.

 

[Vale71]

Then there's a very good chance your water has a very different composition, either because of seasonal fluctuations or depending on where your supplier is actually sourcing the water that comes out of your tap.
Unfortunatly calculations are only as good as the data that you input into them. For starters I definitely would leave out the baking soda, if you still get wildly inaccurate results then you either need a more accurate water analysis or to start brewing with bottled or treated water with a known composition.

 

[troyp42]

Ahh ok so your saying Beersmith is going on my water profile plus the malt bill to get a ph Value so it thinks I need baking soda to raise the PH? But with my last recipe with the baking soda it said the adjusted mash ph was 5.70. With it then out it said it was 5.64 so still too high. So why does it want to add any in the first place unless I was brewing a stout or a darker beer?

 

[Silver_Is_Money]

The amount of 88% lactic acid required to fully neutralize 0.74 grams of baking soda is right close to 0.75 mL of lactic acid.

I would suggest that you purchase an inexpensive aquarium KH test kit. KH is carbonate hardness, or alkalinity as measured in German dH units.

KH x 17.848 = ppm Alkalinity as CaCO3

 

[Silver_Is_Money]

Your addition of 0.74 grams of baking soda was not likely sufficient to raise the mash pH by as much as one tenth of a point. Likely closer to half of that.

Wheat malt has a DI_pH in the vicinity of 6, and unmalted wheats DI_pH is in the vicinity of 6.6. And on top of this your base malt itself may be in the ballpark of 5.75 as to DI_pH. I suspect that perhaps Beersmith underestimated the "effective" alkalinity of one to perhaps all of these grist components with respect to a typical targeted mash pH.

 

[Oginme]

Ahh ok so your saying Beersmith is going on my water profile plus the malt bill to get a ph Value so it thinks I need baking soda to raise the PH? But with my last recipe with the baking soda it said the adjusted mash ph was 5.70. With it then out it said it was 5.64 so still too high. So why does it want to add any in the first place unless I was brewing a stout or a darker beer?

Let's start with this: BeerSmith does not think anything that you do not tell it to. The program is adding baking soda most likely because the water profile you told it to match has a Bicarbonate level around 43 ppm and your base water only contains 13.2 ppm. The model used in the software has only two sources of carbonates: Baking soda and Calcium carbonate. It will try to use one of those to attain the Bicarbonate level which is indicated in your target profile.

The program does NOT adjust the mineral content to reach a pH level. It does try to match the water profile you tell it you want and then tries to calculate the impact the minerals have, in combination with your water profile and the grains being added, on your mash pH. You can then, by entering the estimated mash pH or measured mash pH in the mash tab, get an estimated amount of acid to add to adjust the mash pH to your indicated target. Since the model the program uses overestimates the buffering capacity of the wort, the program does calculate more acid than is actually needed. A rough rule of thumb is to use around 60% of what the program estimates you will need for acid.

 

[Silver_Is_Money]

The nominal pH shifting impact of adding the baking soda addition can be ballpark looked at another way. 12 mL of 88% lactic acid reduced the pH from 5.9 to 5.1, or by 0.8 points. Therefore each full mL of lactic acid reduced the pH by roughly 0.067 points. If 1 mL of lactic acid is very close to the equivalent of 1 gram of baking soda (such that one neutralizes the other at this ratio), then 0.74 grams of baking soda should raise the mash pH by roughly 0.067 x 0.74 = 0.0496 points. Right close to my above educated guess of less than .1 and more likely around 0.05 points. So the effect of adding the baking soda was rather trivial overall, and the mash pH of 5.9 was mainly not as a result of adding the baking soda.

 

[troyp42]

Thanks gents I get it now. makes sense once its explained properly. I have noticed that BS calculates more acid than whats needed and I always put in less than it says to.