I'm sorry
I did edit while you were writing.

airborn wrote:I'm sorry
I did edit while you were writing.

I see this is the part I didnt see...

airborn wrote:All I can test is tds = 152 and pH by a strip to app. 6
Seems moderate corosive in the langlier-index ( I might very well be wrong as I'm not at all good at this )

Don't let that worry you. When the calcium is near zero LSI goes very negative and is meaningless. In general you need to avoid blindly assuming that a negative LSI always indicates corrosivity. I also suspect your actual pH is higher than what you read on that strip.

Hello again

The more I study and try to understand the more questions pop up

Can I - if I like a little more alkalinity in the water - increase the Potassium bicarbonate a bit ?

Where is the limit - for the sake of the espressomachine ?

Will that increase the pH value ?

Could I instead use just at little Calciun Citrate ? and how would that affect the machine?

airborn wrote:Can I - if I like a little more alkalinity in the water - increase the Potassium bicarbonate a bit ?

Yes. That's the most recommended way of increasing alkalinity in the brewing water. It has an advantage over sodium bicarbonate because it will not give you high sodium in the brew. Coffee already has a lot of potassium in the beans, so increasing the potassium a little via the water should not do anything to affect taste.

airborn wrote:Where is the limit - for the sake of the espressomachine ?

If you have calcium in the water, the limit is dictated by the calcium hardness in combination with the carbonate alkalinity. You can do LSI calculations or use Jim Schulman's Insanely Long Water FAQ to get a handle on that. If just using potassium bicarb I think using too much will negatively affect the taste without causing any machine health issues. 100 mg/L (the R Pavlis recipe) is often recommended as optimum, but you could go much more than that and not worry about the machine.

airborn wrote:Will that increase the pH value ?

Yes.

airborn wrote:Could I instead use just at little Calciun Citrate ? and how would that affect the machine?

Calcium citrate will give you a little alkalinity (acid buffering capacity) but not nearly as much as potassium or sodium bicarbonate, and I don't think it's ideal for that purpose. Carbonates and machine health are well understood because they are in natural water. Citrates are not. We had one opinion in the past from the late professor Pavlis (HB member rpavlis) who had the opinion that citrates may not be ideal because they may promote microbe growth in the tank: Third Wave Water .

Hi again Homeburrero

I have now done some messurements on the resulting water .
Taste is fine.

My calibrated pHmeter says 6.6 slooowly raising to 6.8-ish tds: 117 hardness : 113 alkalinity: 40

When I put these numbers ( pH 6.6 version ) in the La Marzocco water calculator it says:
Slightly corrosive but non-scale forming

if I can raise the pH to 7.0 it would be :
Balanced but pitting corrosion possible in presence of chlorides

Should I do that and HOW ?

Is this water that you have formulated using RO water, Epsom salts, and potassium bicarbonate?

If so I think you have water that is fine for the machine irrespective of the La Marzocco water calculator results, which is a somewhat simplistic model and for use with natural water.

airborn wrote:My calibrated pHmeter says 6.6 slooowly raising to 6.8-ish

I'm guessing that it will keep rising as it slowly off-gasses dissolved CO2 from the water.

If you wanted more ease of mind about any potential corrosion risk I think you could add maybe 50% more potassium bicarbonate, getting you around 60 mg/L alkalinity.

Hello all
but with thanks to especially Homeburrero.

I have just checked my mushroom for the first time since you helped me formulate my brewwater

AND IT LOOKS LIKE BRAND NEW

Yours sincerely
Airborn