homeburrero wrote:Yes - The full strength recipe is 100 mg of potassium bicarbonate per liter, which for a US gallon would be 0.38 gram. No need to be precise, appx 0.4 gram per gallon is close enough. Dr Pavlis said that for dark roasts he might use as little as half that amount for taste reasons. The full strength gives you an alkalinity of 50 mg/L in CaCO3 equivalents and have a conductivity of around 120 µS/cm at 25℃, which would read around 60 ppm on an inexpensive TDS meter.

Thank you very much!

homeburrero wrote:Not really. The simple option would be to use a calcite remineralizing filter. It would dissolve small amounts of calcium carbonate into the water. Unlike rpavlis it would have some calcium ion and it would likely have a little less bicarbonate ion than rpavlis water.

Thank you Pat. My understanding of chemistry is basic, so I don't fully appreciate the significance of "likely have a little less bicarbonate ion than rpavlis water".

Would my understanding be correct that using a calcite remineralizing filter after an appropriate RO system would be the simplest / most practical (if not only) route to being able to direct plumb my machine and have great water quality that would greatly reduce or eliminate risks to my espresso machine and provide water that had the potential of producing great tasting espresso? Are there other considerations that would cause one to strongly consider avoiding direct plumbing and go the route of preparing / using rpavlis water and the water tank?

As a bit of background, we have well water and have a whole-house iron filter, water softener and a U/V filtration that has sediment pre-filtration.

Thanks again!

canoehead wrote:Thank you Pat. My understanding of chemistry is basic, so I don't fully appreciate the significance of "likely have a little less bicarbonate ion than rpavlis water".

My point is that many remin filters don't add much mineral. It depends on factors like flow rate and pH, but many people only get 20 - 40 ppm of CaCO3 out of their remin filter, which is less than half the bicarbonate in the rpavlis recipe. Not a big issue since the RO water has very low levels of corrosives like chloride it can get away with a lower than typically recommended bicarbonate alkalinity.

canoehead wrote:Would my understanding be correct that using a calcite remineralizing filter after an appropriate RO system would be the simplest / most practical (if not only) route to being able to direct plumb my machine and have great water quality that would greatly reduce or eliminate risks to my espresso machine and provide water that had the potential of producing great tasting espresso? Are there other considerations that would cause one to strongly consider avoiding direct plumbing and go the route of preparing / using rpavlis water and the water tank?

If plumbing in, yes I think that's probably simplest and most practical. But I'm pretty agnostic about the importance of water as it relates to taste. But depite having said that, I admit that in my own case, where I'm thinking about a new coffee bar with a plumb-in machine, I may still elect to use the CarefreeBuzzBuzz approach. That's partly because I find it easy to schlepp de-ionized refills from my grocery and can avoid issues with cost and maintenance of an RO system.

Thank you Pat for breaking this down for me. I am grateful for you taking the time to share your expertise / experience / knowledge.

The CarefreeBuzzBuzz approach is impressive, but it is a bit more than I could undertake at this time. I think that I'll start by updating my RO including, as advised, a calcite remineralization filter and then direct plumb to the Bianca. This water should be good tasting for espresso, it will be safe in preventing corrosion and scale build up and will also continue to be great drinking water for my family.

At some point, I may disconnect that setup and try rpavlis water using my RO in the water tank and compare the taste of both of those options.

Final questions:
• Do you have specific RO systems / manufacturers that you would recommend (or not)? I'm presently looking at a Hydrotech Aqua Flo 475 - a 4-stage, 75 GPD solution
• Would you include a booster pump on the RO?
• Is there a particular calcite remineralization filter that you would recommend or are they all pretty much the same?

Thank you!

canoehead wrote:Final questions:
• Do you have specific RO systems / manufacturers that you would recommend (or not)? I'm presently looking at a Hydrotech Aqua Flo 475 - a 4-stage, 75 GPD solution
• Would you include a booster pump on the RO?
• Is there a particular calcite remineralization filter that you would recommend or are they all pretty much the same?

Sorry but I don't have direct experience with RO systems. From what I've seen here on HB it seems that people are generally happy with the common affordable Apec, Homemaster, iSpring, systems. For more expensive cafe quality options with precision bypass/blending a lot of people go with Optipure. The only RO systems that I found to be sold by one of the HB sponsoring espresso equipment vendors are the Everpure and Optipure systems from Prima coffee. Some more info in this thread: Slayer - need advice on RO water system for LA area

If your pressure is low then for sure use a booster pump. For any of them a permeate pump is probably beneficial. It's not really an electric pump, just a system that removes pressure from the output side of the membrane.

The advantage of simple calcite or crushed marble is that it's predictable in doing just what you need (adding small amount of calcium carbonate) and won't over-correct the mineral. Some remin filters add a small amount of Corosex (MgO beads) which will give you a little magnesium and more pH correction which I think is also fine. There are a few that also include some trace minerals that appeal to various health faddists that probably are harmless (See end of this post: ECM Synchronika Complete Rebuild ).

Pat... Thank you very much for so patiently filling in the blanks with respect to RO and remineralization ultimately setting me on the right path.

As I'm completely updating our existing water treatment equipment, I'm starting with a full / detailed lab analysis on our water. I don't expect major changes since the last analysis 6 years ago, but given imminent expenditures, it's best to fully inform all decisions. I'll then proceed with updating our whole-house iron filtration, water softening and an RO system that includes a permeate pump and calcite remineralization.

This topic has been my first activity on Home-Barista. Your generosity in sharing your deep knowledge is admirable and much appreciated.

Kind regards,
Kevin

HEllo!

Is somebody still here?
How true can it be that using Rpavlis recipe killing the "acids" in my coffee?

4go wrote:How true can it be that using Rpavlis recipe killing the "acids" in my coffee?

Rpavlis contains bicarbonate, and any bicarbonate will have a buffering effect on acids. For example, potassium bicarbonate will react with citric acid to form potassium citrate.

But the amount of bicarbonate in rpavlis is moderate compared to typical waters, and is much lower than what you get in water with even moderate amounts of hardness. Typical coffee water recommendations recommend an alkalinity (acid buffering capacity) in the range of 40-100 mg/L CaCO3 equivalent. Lower than that is not recommended for espresso equipment for corrosion risk reasons. Higher than that is typically not recommended because it may dull the taste of the coffee. Rpavlis is only 50 mg/L alkalinity so should not be a problem, especially for espresso. (Espresso tolerates far more alkalinity than brewed pourover coffee.) Some people (including Dr Pavlis) have said that, for some coffees, they prefer the taste when using half as much potassium bicarbonate as the standard recipe.

Thank you for your answer!
May I ask some questions?

Typical coffee water recommendations recommend an alkalinity (acid buffering capacity) in the range of 40-100 mg/L CaCO3 equivalent. Lower than that is not recommended for espresso equipment for corrosion risk reasons.

-Is the recipe (100mg/L) has 50mg equivalent CaCO3? (i started the thread because protecting my machine has higher prio than taste and i want to be 10000000% sure that the recipe i use i protect the machine especially the stainless steel boilers - Profitec Pro 700 - )

Some people (including Dr Pavlis) have said that, for some coffees, they prefer the taste when using half as much potassium bicarbonate as the standard recipe.

Based on what you wrote above, this means that they risk the corrosion of their machines?

Thank you!

4go wrote:-Is the recipe (100mg/L) has 50mg equivalent CaCO3?

Yes. (The molar mass of KHCO3 and CaCO3 happen to be about the same - 100 g/mol - but a CaCO3 molecule neutralizes two H⁺ and a KHCO3 molecule neutralizes only one. So 100 mg/L of KHCO3 is chemically equivalent to 50 mg/L of CaCO3.)

4go wrote:Based on what you wrote above, this means that they risk the corrosion of their machines?

Not really in this case. "At or above 40 mg/L" is a reasonable rule for most water, but because this recipe is devoid of any corrosives like chloride or sulfate you can safely go lower. The pH difference at 25 mg/L vs 50 mg/l (as CaCO3) is not large - for a purely potassium bicarbonate solution at equilibrium with air at 25 ℃ it's around 7.9 vs 8.2. Either will be nicely non-corrosive and will favor maintaining the protective copper oxide layer on copper and brass.