Additives to raise pH of distilled water?

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
User avatar
EddyQ
Posts: 1035
Joined: 8 years ago

#1: Post by EddyQ »

I've been making recipe water for espresso for about a year now and wondering how close to 7 is distilled water and if there is a common additive to raise it just a notch. Anyone use a pinch of something?
LMWDP #671

PBJ
Posts: 47
Joined: 9 years ago

#2: Post by PBJ »

Baking soda will raise the Ph

User avatar
EddyQ (original poster)
Posts: 1035
Joined: 8 years ago

#3: Post by EddyQ (original poster) replying to PBJ »

Yes, but it will also increase alkalinity. I have read that Soda Ash (sodium carbonate), which can be made by baking baking soda for a hour or so at 200F will make Soda Ash and is a common additive for raising PH. But will it add flavor or do bad things to my espresso machine?

And how much? Assume all I want to do is raise the PH of distilled water from 7 to 7.5, then mix the standard Rpavlis recipe or use a Epsom Salts/Baking Soda recipe. The purpose would be just to prevent a mix with PH less than 7 and stop all chances of corrosion in my espresso boiler.
LMWDP #671

User avatar
homeburrero
Team HB
Posts: 4863
Joined: 13 years ago

#4: Post by homeburrero »

Sodium or potassium bicarbonate is probably the best way to raise the pH. It will raise the alkalinity but the two go hand in hand in water that has dissolved CO2 and carbonates.

You can manipulate the pH above or below what is normally predicted by the alkalinity by adding or removing CO2.

A trick sometimes used by water utilities to remove CO₂ is to add calcium hydroxide, Ca(OH)₂ (aka slaked lime, limewater, pickling lime). Then you get the reaction:
Ca(OH)₂ + CO₂ → CaCO₃(s↓) + H₂O

Removing CO₂ drives the removal of carbonic acid, H₂CO₃ from the water. The calcium carbonate is then precipitated and filtered off. This keeps the pH high in the plumbing system, but if the water is exposed to air it will pick up CO2 from the atmosphere and return closer to the pH predicted by the alkalinity of the water.


People sometimes lower the pH by using a sodastream spritzer to add CO₂. The CO₂ combines with H₂O to produce carbonic acid, H₂CO₃ , and carbonic acid dissociates to H⁺ and HCO₃⁻ ions. The effect is temporary if the water is exposed to air and the high dissolved CO₂ escapes to the air.

Here's a picture relating CO₂ to the carbonates (HCO₃⁻ and CO₃²⁻) involved in alkalinity that may be helpful

Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

User avatar
homeburrero
Team HB
Posts: 4863
Joined: 13 years ago

#5: Post by homeburrero »

EddyQ wrote:wondering how close to 7 is distilled water and if there is a common additive to raise it just a notch.
Getting back to your initial question, you can add about 5 mg of sodium bicarbonate (baking soda) to a liter of distilled and if that water is exposed to atmospheric CO2 it should equilibrate to a pH of 7.0 at 25 C.* That's an extremely tiny amount and would have an alkalinity of only around 3 mg/L CaCO3 equivalent.

If using in an espresso machine this water might have insufficient alkalinity. Better advice would be to add enough bicarbonate to get the alkalinity higher, as in closer to 40 mg/L. The R Pavlis recipes advocated often on this site do a good job of that.


*(I used http://www.aqion.onl/show_ph to do this calculation)
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

User avatar
EddyQ (original poster)
Posts: 1035
Joined: 8 years ago

#6: Post by EddyQ (original poster) »

homeburrero wrote:Getting back to your initial question, you can add about 5 mg of sodium bicarbonate (baking soda) to a liter of distilled and if that water is exposed to atmospheric CO2 it should equilibrate to a pH of 7.0 at 25 C.*
I checked PH of my Potassium Bicarbonate concentrate, which has been mixed and stored in a 1liter plastic soda bottle for almost 1 year and PH measured 8.3. Mixed it with distilled water per recipe and PH dropped, but was still above 7. Seems like I should stick with Rpavilis recipe since it nicely keeps PH above 7.

However, this bit about atmospheric CO2 got me wondering if the PH is stable vs time if left open to room air. Or if my plastic soda bottles mix CO2 with the solution over time. Based on what I measured above, I think I don't have any issues. Soon I hope to go to a large 5gal mix and haven't decided on the details. I have some glass carboys from my days of home brewing beer. Maybe those would be best, since they should seal out the atmosphere.
LMWDP #671

User avatar
homeburrero
Team HB
Posts: 4863
Joined: 13 years ago

#7: Post by homeburrero »

EddyQ wrote:I checked PH of my Potassium Bicarbonate concentrate, which has been mixed and stored in a 1liter plastic soda bottle for almost 1 year and PH measured 8.3. Mixed it with distilled water per recipe and PH dropped, but was still above 7. Seems like I should stick with Rpavilis recipe since it nicely keeps PH above 7.
Yes, If using the rpavlis formula your pH will be fine irrespective. The bicarbonate acts as a buffer of acidity. Even if you go down to the half strength formula (i.e., 50 mg/L rather than the usual 100 mg/L of potassium bicarbonate) your pH will be fine. No need to worry about sealing or not sealing carboys or reservoirs.
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h