Warning: Chloride & sulfate levels with weak acid cation softeners (e.g., Everpure Claris) - Page 2
- shadowfax (original poster)
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OK, you got me on the "mineral" thing. Yes, technically minerals are any solid that can precipitate out of water. In the context, I meant calcium and magnesium, i.e. general hardness (GH); sorry that wasn't clear. To be clear, not all cation softeners are created equal.Peppersass wrote:Water produced by cation softeners can have plenty of mineral content. What it lacks is carbonate hardness or GH.
Salt-charged cation softeners reduce GH (i.e., they replace the magnesium and calcium cations with sodium or potassium ions) without reducing the carbonate hardness (KH). This type of softener is generally very safe for espresso machine boilers because there is no pH reduction. You also don't see these systems offered with blending. This is presumably because if you put back a meaningful level of minerals without reducing the carbonates, you will just end up with water that scales a little slower, rather than "boiler safe" water.
Hydrogen-charged weak-acid cation softeners, by contrast, reduce carbonate and general hardness. The hydrogen cations dissolve the carbonate into water and carbon dioxide, in addition to removing the magnesium and calcium. This causes a pH reduction, and if used alone will result in water with an equilibrium pH around 6. For that reason, you need to blend this water with unsoftened water to get to a neutral equilibrium pH (7) to prevent corrosion. In the process, with most waters, you also raise the GH as well. This allows you to get water that is boiler safe without almost totally eliminating the magnesium and calcium.
Hence why I specifically referred to salt-based cation exchange, because it doesn't cause the type of concerns with sulfates and chlorides that this post discusses. I don't think this falls in the category of weak-acid cation exchange, but I am not sure. If it does, then I don't think it's fair to lump it together with the hydrogen type. Here's some reference measurements I made years ago that make this crystal clear.
Nicholas Lundgaard
- shadowfax (original poster)
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Very interesting; I'll look forward to reading about that.another_jim wrote:This is not quite your desire; but in practice, salt softeners are used when the water is so hard that RO style systems are extremely wasteful. In particular, people are curious how a coffee made with water from a whole house salt softener stacks up. I personally am looking forward to the results, since this kind of information is my reward for doing these public gigs.
Indeed, I was very curious about this when a member posted about it last year, but it seems that Everpure have no plans to bring it to the US.post meridiem wrote:I wonder if their new 'Ultra' line (http://www.pentairfoodservice.eu/pdfs/C ... _17123.pdf) addresses some of the low-pH problems. Seems to be designed around just that, but I don't believe they have a U.S. distributor yet.
Nicholas Lundgaard
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A lot of really useful information; thanks for sharing it. We're a long way from "it's just coffee" here ...
The city actually has plans to fix the high sulfate issue, but since it's well within the EPA range, who knows how long that'll take.
That's too bad. My water measurement yesterday wasn't promising (7.4 equil. pH based on alkalinity, and water pH in the 5s!), and this new Ultra system may have been the answer. But the testing strips were a few years old, and I do like the simplicity of the Claris system (and have it set up just so in my plumbed setup), so I'm thinking that I'll get a fresh small cartridge (current one is old), some fresh ph, alkalinity, and hardness strips, and do some new measurements. If it's still too acidic in a few months, I'll retool the setup.shadowfax wrote:Indeed, I was very curious about this when a member posted about it last year, but it seems that Everpure have no plans to bring it to the US.
The city actually has plans to fix the high sulfate issue, but since it's well within the EPA range, who knows how long that'll take.
- Peppersass
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- Joined: 15 years ago
While I'm not so sure that GH is necessary to produce the best coffee, there's plenty of evidence that GH affects extraction in some way. In the extreme case, comparisons between coffee made with RO and water with a certain minimum GH level bear this out.
What we don't know is exactly how GH affects extraction. Does it simply increase the extraction yield or does it change the proportion of the flavor compounds that are extracted? Or both?
And if we replace the Ca/Mg with Na, then how are both extraction yield and proportion of flavor compounds affected?
My memory is vague on this, but I recall seeing a study that suggested GH ions decrease the amount of CO2 released, thus improving extraction yield. If it's just a matter of increasing extraction yield, then it may be possible to compensate for the absence of GH ions by any number of methods, including grinding finer, increasing temperature, etc. But if a certain minimum level of GH results in a more favorable ratio of various flavor compounds, then there's no doubt we need some hardness to produce the best coffee.
We can measure the extraction yield with relatively inexpensive tools. But measuring the proportions of flavor compounds takes much more sophisticated equipment.
What we don't know is exactly how GH affects extraction. Does it simply increase the extraction yield or does it change the proportion of the flavor compounds that are extracted? Or both?
And if we replace the Ca/Mg with Na, then how are both extraction yield and proportion of flavor compounds affected?
My memory is vague on this, but I recall seeing a study that suggested GH ions decrease the amount of CO2 released, thus improving extraction yield. If it's just a matter of increasing extraction yield, then it may be possible to compensate for the absence of GH ions by any number of methods, including grinding finer, increasing temperature, etc. But if a certain minimum level of GH results in a more favorable ratio of various flavor compounds, then there's no doubt we need some hardness to produce the best coffee.
We can measure the extraction yield with relatively inexpensive tools. But measuring the proportions of flavor compounds takes much more sophisticated equipment.
- JohnB.
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What are you considering a "meaningful" level of minerals? I use the generic salt based softener cartridges followed by a carbon filter with a mixing valve leg to add hard water (well water tests at 8 grains currently) back between the two filters. I keep the valve set so I get water going into my machine that tests right in the 2-3 grain cusp. This keeps the scale at bay and gives me an acceptable compromise between the taste of the fully softened water which I do not care for & our hard well water which tastes pretty damn good IMO.shadowfax wrote: Salt-charged cation softeners reduce GH (i.e., they replace the magnesium and calcium cations with sodium or potassium ions) without reducing the carbonate hardness (KH). You also don't see these systems offered with blending. This is presumably because if you put back a meaningful level of minerals without reducing the carbonates, you will just end up with water that scales a little slower, rather than "boiler safe" water.
LMWDP 267
- shadowfax (original poster)
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- Joined: 19 years ago
It depends on how high your alkalinity is. Also on whether it's a steam boiler or a brew boiler. There is a table of maximum non-scaling hardness by alkalinity and temperature on page 4 of the water FAQ. It only displays up to 70 ppm of alkalinity-if your alkalinity is higher, the max hardness will be lower, and the page contains the formula for calculating this.JohnB. wrote:What are you considering a "meaningful" level of minerals?
Nicholas Lundgaard
- JohnB.
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Looking at those charts/tables I seem to be in good shape. PH = 6. so alkalinity is 10?? according to the table. Steam boiler set to 2.2 bar (272F).
LMWDP 267
- shadowfax (original poster)
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I suggest you measure alkalinity directly. The table you read that number fromrelates alkalinity to equilibrium pH. pH measured with a strip can be impacted by other factors, and you can't work 'backwards' like that. Also, a pH of 6 is on the low end of corrosion-safe (see also: various water recommendations from manufacturers/SCAA), and might be a cause for concern if it's not from dissolved CO2. If your alkalinity is high (100+ ppm) as would be expected from a hard well water source, a pH reading that low seems pretty strange to me. I'd be wondering if there's something wrong with the test strips (or whatever you used to meter it).
Nicholas Lundgaard
- JohnB.
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I use an API PH test kit which uses drops of solution, not strips. That should have been 6.6 PH not 6. So much for going by memory! I've had the boilers open several times since 2009 & have never found any signs of corrosion. Last in there in November 2012 & all I found was a light coating of scale on the heating element which I cleaned off in my blast cabinet.
LMWDP 267
- shadowfax (original poster)
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- Joined: 19 years ago
Great. 6.6 should be boiler safe, as far as I know, and obviously the evidence you have over long-term use backs that up. I bet your alkalinity is close to neutral, but again you need to actually use the KH test to find out for sure, measuring pH is not an accurate proxy for it.
Nicholas Lundgaard