bettysnephew wrote:If I made a mix with Sodium Bicarb vs. the Potassium bicarb I have been using, would there be any possibility of corrosion damage to my boiler?

No, neither of those bicarbonates is at all corrosive. Potassium has the theoretical advantage that it's a mineral that coffee itself is loaded with, so you aren't adding anything that isn't already there in abundance.

Strifer wrote:Assuming the rpavlis water recipe is purposed for espresso, is there an alternative recipe to maximize both brew and espresso?

You can use it for both. At full strength the alkalinity is about 50 mg/L, which isn't that high. You can try half or less strength rpavlis for brewed coffee if you think that might be an issue. (Some argue that high alkalinity can neutralize the acidity of brewed coffee, making it taste dull. Typical advice is to keep it below 100 mg/L. )

Thanks Pat, I thought that to be true but wanted confirmation. Mostly just curious regarding possible taste differences as I am sensitive to certan tastes. Don't like the flavor of small quantities of Epsom salts for some reason.

Hey All,

Did some rpavlis water making tonight. 100mg of Potassium Bicarbonate thrown in and mixed into a full 1L bottle of ZO filtered water.

Did a quick TDS scan on it (using the ZO tester), and it yielded a TDS of 48. Seems a bit low compared to what i've read here.

Thoughts?

DonCon wrote:Did a quick TDS scan on it (using the ZO tester), and it yielded a TDS of 48. Seems a bit low compared to what i've read here.

That's within expectations. The expected conductivity of a 100 mg/L KHCO3 solution at 25℃ should be 116 µS/cm, On an NaCl calibrated 'TDS meter' would read about 60 ppm, and that's what many people are reporting with their inexpensive TDS meters. If the water temperature is not 25C or if the meter is out of calibration it can be quite a bit off from that.

homeburrero wrote:That's within expectations. The expected conductivfity of a 100 mg/L KHCO3 solution at 25℃ should be 116 µS/cm, On an NaCl calibrated 'TDS meter' would read about 60 ppm, and that's what many people are reporting with their inexpensive TDS meters. If the water temperature is not 25C or if the meter is out of calibration it can be quite a bit off from that.

Thx for confirmation and quick reply. I took this reading on water that had been refrigerated already.

I measured the same bottle of Rpavlis water today, but left it on the counter overnight (room temp). It measured 70s in TDS with same meter.

Makes more sense now.

Stanford55 wrote:Recipe #2: 3.8g potassium bicarbonate/distilled water concentrate mixed with 1 gallon of distilled

Are you sure about this number? It's seems off by a factor of 10 compared to other users in this thread:

sweaner wrote:I simply add 400 mg potassium bicarbonate into 1 gallon of distilled water.

Sideshow wrote:I bought a milligram scale and a 1000 ml container. I just pour 100 mg of potassium bicarbonate into 1000 ml of distilled water and then put that into my machine. It can't get any simpler than that.

After normalizing, these translate to the following 3800 mg per 1 gallon (Stanford55) vs. 400 mg and 380 mg per per 1 gallon (sweaner and Sideshow)

Stanford55, in case this wasn't a typo and you're actually putting this much into a gallon, it would be interesting to see the same taste test with 1/10th the amount, and whether the testers would still prefer it over TWW.

Am I reading this right if I was to do Recipe 1 for dark roasts (50% strength), I would add .19g of potassium bicarbonate to 1 gal of distilled water if I bypassed making the concentrate?

ethiopianbuffman wrote:if I was to do Recipe 1 for dark roasts (50% strength), I would add .19g of potassium bicarbonate to 1 gal of distilled water if I bypassed making the concentrate?

Correct. Simple recipe math here: You want 50 mg/liter. multiply that by 3.8 liter/gallon to get 190 mg/gallon, then divide by 1000 mg/g to get 0.19 g/gallon.

Stanford55 wrote: Recipe #1: 5 gallon RO water mixed with the appropriately sized Third Wave Water espresso packet yielded: 187ppm/70 alkalinity.
Recipe #2: 3.8g potassium bicarbonate/distilled water concentrate mixed with 1 gallon of distilled water yielded: >17.1ppm/50 alkalinity.

boren wrote:Are you sure about this number? It's seems off by a factor of 10 compared to other users in this thread:

I'm not Stanford55, but that sure looks like a typo - probably meant to type 0.38 g in one gallon. If he had used 3.8 gram his Hach kit would have tested way up the scale with 250 500 mg/L CaCO3 equivalent alkalinity. (BTW, I'm not sure I understand his alkalinity numbers. Half Full strength rpavlis should be about 25 50 mg/L CaCO3 equivalent, or 1-2 3 drops on a Hach drop kit test. )

Edit corrections: The half strength 50 mg/L KHCO3 that ethiopianbuffman wants has only 25 mg/LC aCO3 equivalent alkalinity. Stanford55 was using full strength (100 mg/L KHCO3) and I initially got the two of those mixed up.

Ok now I know why people don't add .19g to 1 gal because it is tedious to get that amount.

I am glad I don't have to use the charcoal filters in the BDB anymore now.