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homeburrero wrote:I use powdered CaCO3, MgCO3, and KHCO3. I add about 1g of each to a 750 ml swingtop stoppered bottle for my concentrate. That concentrate is cloudy with undissolved CaCO3, so I need to shake well before using. I add a shotglass (~44ml) of that to 3L of purified water in a gallon glass jar get my brew mix. If I let that sit a while all precipitate dissolves fully - I never see precipitate in the bottom of the gallon jar. Generally on my Giotto I'm even lazier - every night I simply fill the reservoir direct from the Zerowater jug, then followup with a partial shot of my concentrate (shooting for roughly 40 ml per full reservoir tankfull.)

I'm not a true believer in this mix. It's easy for me, but I'm not convinced it's any better than simple 100 mg/L KHCO3 (rpavlis) water. Like the rpavlis water, my water has good alkalinity and zero chloride or sulfate, which appeals to my paranoia about brass and copper corrosion in my older espresso equipment.

Perhaps off topic, but I've tried to use this recipe and wasn't very successful.
I've created the concentrate, which was indeed cloudy.
After letting it sit for a few days in the fridge, the CaCo3 sank down to the bottom of the bottle.
Just before preparing the water, I shook the bottle well and the water became cloudy again.
Then I measured 44ml to be added to 3L of distilled water.
My resulting water measured 1-2dKH and also GH was rather low.

What am I doing wrong? Should I have poured the 44ml quicker? How fast does the CaCo3 sink after shaking the bottle?
Is it possible that I've made some mistake when creating the concentrate (though I was very careful while preparing it)?
Any idea or advice?


Moderator note: This and the following 5 posts originally were posted to the topic How pleased are you with ZeroWater solution? and were split to this new topic

MonLon wrote:Perhaps off topic, but I've tried to use this recipe and wasn't very successful.
[...] Is it possible that I've made some mistake when creating the concentrate (though I was very careful while preparing it)?

As long as you get the amounts right I think you should be OK. I give it a good shake and immediately pour off (less than 2 seconds) my shot of concentrate, and over time my concentrate bottle doesn't seem to get more or less concentrated. Everything that goes into my bottle eventually goes into the reservoir so it has to average out. I just did a careful mix of a new 3 liters, and tested myself (API GH and KH kit, boosted to 10 ml sample (9.8 mg/L CaCO3 equivalent per drop) , and came out as I'd expect - about 6 drops for KH and about 4 - 5 for GH.

Some ideas - store your salts in sealed containers and dry space. All are mildly hygroscopic and can absorb moisture in humid environments. The KHCO3 will form hard lumps if it absorbs a little moisture. But I think this would not drop you much. I oven-baked some lumpy KHCO3 once and found that it had gained less than 5% moisture.

Also, for the API GH test I think you need to give the mix a day or two before titrating - make sure it's nice and crystal clear and the carbonates are well dissolved over to bicarbonate, Ca(HCO3)₂ otherwise I think you won't see that orangish starting color that goes greenish at the endpoint. I expect the Hach total hardness kit may work better here.

homeburrero wrote: My homemade is currently a simple mix of equal mass amounts of calcium carbonate, magnesium carbonate, and potassium bicarbonate to produce a water with a total hardness of ~44 mg/L and total alkalinity of ~54 mg/L as CaCO3. That gives me water roughly similar to what they use in WBC competitions and is very easy for me to mix up. I can't say that this mix is really any better than if I were to use nothing but potassium bicarb at a similar alkalinity level.

Pat where do you purchase these ingredients? I will have to switch to a water recipe when we move to AZ. I was going to go with some six gallon tanks. Thanks Michael

Many thanks Pat.
Helpful as always
I'll give it another go and hope it will turn out better.

homeburrero wrote: and micronized MgCO3 by Bulk Supplements.

For those who like calculating stuff keep in mind this isn't simple MgCO3 but the dypingite version with formula: 4MgCO3 - Mg(OH)2 - 5H2O

You might need to adjust your weights accordingly.

(They don't say it's dypingite anywhere on the packaging/website but it's rare to see simple MgCO3 - at least when I've looked for it. You can also see that they say you get 385mg of magnesium for 1540mg of powder which is inline with the molar masses in the dypingite formula assuming I haven't made a dumb formula error [certainly wouldn't count it out!])

More geeky info about the Bulk Supplements MgCO3 calculation....

homeburrero wrote:I had looked into it and thought the Bulk Supplements product was simple pure magnesium carbonate, but I think you are right here - they do say their product is 25% elemental Mg, and say it again with that 385 mg in 1540 mg of powder, which would be spot on for dypingite.

Looking further it gets complicated. I've come across different labels, some of which appear to be in error, so I contacted Bulk Supplements customer support.

They get various minerals from different sources, and it may not be simple pure dypingite. They label it all MgCO3 (because it does dissolve to form magnesium bicarbonates). When they change their source, it goes to their QA department who come up with a new label, and the fine print on your label is your only clue to the amount of Mg you get out of a gram of their product.

And that fine print can be confusing:



The trick to figuring the doses from these labels is to first ignore when they say (as Magnesium Carbonate). That's clearly wrong, and their customer support rep assured me that these 210 mg, 50% of daily value numbers are always quantified as elemental magnesium. So then you just look at the sample size and do the math. The one on the left is 210/875 = 24% elemental magnesium, and the one on then right is 210/750 = 28% elemental magnesium. Pure dypingite would be 25% elemental Mg and pure MgCO3 would be 29% elemental Mg, so fortunately in the samples we've come across so far it doesn't make a big difference if you were to calculate based on it being pure MgCO3.

(To convert elemental magnesium to MgCO3 you would multiply it by 3.47, and to convert it to CaCO3 equivalent you would multiply it by 4.12)

P.S.
Another product that some may be using is the USP Basic Magnesium Carbonate from Chemical Store Inc. And they have a different product label approach. They specify the percentage as dry basis MgO. For example "MgO (Dry basis): 42%". Molar mass of MgO is 44.3 g/mol, and molar mass of Mg is 24.3 g/mol, so this example works out to 23% elemental magnesium.

MonLon wrote:Perhaps off topic, but I've tried to use this recipe and wasn't very successful.
I've created the concentrate, which was indeed cloudy.
After letting it sit for a few days in the fridge, the CaCo3 sank down to the bottom of the bottle.
[..]
Any idea or advice?

I don't understand the point of adding the calcium carbonate

1. The solubility of CaCO3 is very low at 47mg/L
   https://en.wikipedia.org/wiki/Calcium_c ... Solubility
2. It (basically) get's less soluble as temperature rises and offgasses CO2 dropping out as limescale
3. Unless you are getting distilled water you are probably get some calcium carbonate

I have not tried it, but I'm guessing what happens with his "fill it in a jar and let it sit" is that the calcium carbonate-bicarbonate balance is shifted by absorbing CO2 from the air and gradually the cloudyness goes away, but a lot of that extra CO2 is going to boil off when the water is heated and wont be coming back unless your boiler is vented in some way.

I'm not sure what the concentration of calcium carbonate is in hard water after it's boiled and rested in a kettle with added potassium bicarbonate, I'm guessing not far from 20mg/L?

Simon Olesen wrote:I don't understand the point of adding the calcium carbonate

1. The solubility of CaCO3 is very low at 47mg/L
   https://en.wikipedia.org/wiki/Calcium_c ... Solubility
2. It (basically) get's less soluble as temperature rises and offgasses CO2 dropping out as limescale
3. Unless you are getting distilled water you are probably get some calcium carbonate

Note that the solubility number you quoted from Wikipedia is expressed in terms of [Ca⁺⁺] ion. In terms of CaCO3 it would be 117 mg/L. My recipe has only around 16 mg/L CaCO3 in the final mix. Points 2 and 3 are true. This recipe is based on purified water with negligible CaCO3 already in it, and the amounts of calcium and carbonate in the recipe are low enough that it should not drop scale even at steam boiler pressures and temperatures. (A Langelier Saturation Index calculation at 130 ℃ gives me a CaCO3 saturation pH of 7.2)

As to what's the point of the calcium carbonate, that is a good question. I do it only because it's easy and it makes my water resemble a soft natural water or an RO that comes out of a remin cartridge. That means it's likely to be similar to the water that a roaster might be using to taste and tune their coffee. It's also along the lines of the water they now use at WBC competitions. It does have zero sulfate, chloride, or silica, but I see that as a good thing for espresso machine health.

With respect to machine health it's no better than the rpavlis recipes that have no hardness minerals at all, and although some would argue that hardness minerals are needed for tasty extractions I can't say that I'm convinced of that.