Sorry. Need some spoon feeding on the topic of water

Cuprajake Not Dave, but yes, you are totally correct. If you use R Pavlis’s recipe, no scale. I just like the flavour with Magnesium… (possibly a ‘problem’ due to my preference for dark roasts - we are finding Black Cat’s Chocolate Point a bit too acidic, even brewed at 90 °C)

CoyoteOldMan Black Cat’s Chocolate Point

Wow! You may try 1 or 2C higher I pulled at 92/98.

I feed the default remineralised RO. On an average, over the last 1 year, , the feeding water had the general hardness of 9 mg/l, alkalinity of about 40 mg/l and TDS of 35-45. The steam water averaged about 18 mg/l to 20 mg/l, the alkalinity of 45 mg/l to 50 mg/l and the TDS of 75-80.

Cuprajake If using potassium there should be nothing to scale. @DavecUK am I correct

You are correct, I don’t believe potassium carbonate scales….but over time the service boiler concentration will rise, at which point you should refresh the water once it gets above a level you are comfortable with.

dutchy101

Correct no need

It’s a very easy mix, make a concentrate. Then dose that to the water

10g potassium bicarbonate to 1litre rodi/distilled water

Then 10g of the concentration to 1litre of rodi/distilled water for the machine.

You can go more, you can go less.

I believe the thinking behind it is that coffee is full of potassium so you don’t notice it, while using different water influences the taste.

I’ve never really know any difference.

I could try using ashbeck for a month to see if I did I suppose.

dutchy101 Is it the same principle, as in adding the potassium to bring up alkalinity to the desireable level (67 mg/l)?

Sodium or potassium bicarbonate - same principle (re: alkalinity and scaling); just adjust to the different molecular weight. Only potential difference is that coffee is quite rich in potassium, so potassium is supposed to alter the taste less. Does it? I don’t know!

CoyoteOldMan My belief is that sodium ions in the water allow the human taste buds to work better….as it is a “flavour enhancer”, or perhaps flavour suppressor might be a better term, allowing you to taste other flavours better. My belief is potassium does this also, but not as well as sodium.

But does sodium scale?

Nope. Only calcium and magnesium (to any significant extent, at the temperatures, concentrations and pressures encountered in coffee making).

Umm,

May try it next batch of water.

I used to use all this stuff for my marine fish

I’ll try to find the weights for the sodium bicarbonate, there’s also sodium carbonate which is stronger haha

Cuprajake I’m not sure that Na₂CO₃ will work as an alkaline buffer (i.e. stabilising acidity) - it will definitely modify pH and alkalinity, but it may well work.

For NaHCO₃ (sodium bicarbonate) instead of KHCO₃ , just multiply whatever weight you were using for potassium by 84% (i.e. 8.4 grams instead of your ‘usual’ 10 grams for the concentrate)

Knluk Is these two sentences the same meaning?

No - first step produces a litre of concentrate (so you can measure fairly accurately how much bicarbonate you are adding, instead of going into fractions of a milligramme). The second step dilutes the concentrate to what is actually needed for brewing.

Knluk What is service boiler concentration? Refresh means draining all the water out then replace with new water?

As you draw steam from the service boiler, whatever salts are in the boiler water get progressively more concentrated (the steam contains no salts) - thus they can scale and/or corrode the boiler. Refreshing is draining and replacing with new water - ideally, for a service boiler, with a low concentration of anything!

The steam is evaporation.

As you evaporate water to get steam the water left gets stronger, and stronger.

The steam is what you would make distilled water from if you let it cool. So all the bad stuff is left in the boiler. Do this enough with bad water you get scale.

Re the sodium carbonate. Don’t use that it’s too strong. That was just my question

Knluk KHCO3 (potassium bicarbonate) - 80 mg/l - for avoid scaling and if use sodium bicarbonate can also enhance taste?

The purpose of potassium (or sodium) bicarbonate is not to “avoid scaling”. Water for brewing coffee needs some alkalinity to taste good (and some alkaline buffer will also help with corrosion - pure water can become acidic by absorbing CO₂ from air). However, potassium or sodium bicarbonate by itself will not create scale.

Knluk the Magnesium can help avoiding scaling

Quite the opposite, unfortunately. Magnesium and calcium salts are likely to cause scale. Magnesium (carbonate) is more benign than calcium - partly because it doesn’t tend to ‘stick to itself’ as much as calcium carbonate does, and partly because it creates less amount of scale to start with. However, water containing (bi)carbonate ions and calcium or magnesium ions in quantities generally believed to be ‘good’ for making coffee will scale.

Knluk Does steam boiler has a scaling point? How can I check the point? Reload with pure water? Does it need to be mineralised pure water?

Dissolved minerals in a steam/service boiler will tend to get more concentrated over time, as steam is extracted but none of the minerals/salts in the water. If you use the spreadsheet that @Rob1 has created, it has a page to help you predict ‘when’ it will scale, depending on your water characteristics and usage, but the TL;DR message is “it will scale if you use calcium and/or magnesium”.

It is a good practice to dilute the minerals by discharging some mineral-rich water regularly (every day) and replacing it with (at least) brewing water. Even better is to empty the boiler regularly, and re-fill it with de-mineralised water.