Warning: Chloride & sulfate levels with weak acid cation softeners (e.g., Everpure Claris)

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
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shadowfax

#1: Post by shadowfax » Jun 18, 2014, 6:07 pm

Around 5 years ago, I started a thread about an interesting new product, Everpure Claris, which allows the user to adjust the softening level of their water to retain much of the mineral hardness in their water while reducing or eliminating the risk of scaling.

The core technology in Claris is weak acid cation (WAC) exchange softening, which uses a bed of Hydrogen (H+) ions to remove the carbonates from water, as explained in their product literature. This is fundamentally a pH reduction; the trick with Claris is that it can be blended with non-softened water to dial the alkalinity/pH reduction just right. It is perfectly safe when used correctly. When alkalinity is reduced too much, serious corrosion can occur. As discussed in that original thread, this goes with the territory of many products: they must be used correctly, and you use them incorrectly at your peril.

Having said that, a number of people have found that their pH appeared to be reduced significantly more than their alkalinity would suggest. I believe that this has generally been explained away as potentially arising from dissolved CO2 in the water (which is also a byproduct of Claris' ion exchange, as well as the atmosphere). This weak carbonic acid usually doesn't persist in boiler water, and isn't a cause for concern.

However, but I want to call your attention to another potential cause for an unusually low pH reading after using Claris for filtering your water: chloride (Cl-) and sulfates (SO4(2-)). These anions are not typically present in significant concentrations in municipal water, but if they are, they can interact very poorly with the Claris softener (or any other WAC ion exchange softener). The H+ that is bled into the water by the ion exchange forms hyrdochloric (HCl) or sulfuric (H2SO4) acid that can reduce the pH dangerously and lead to corrosion of stainless steel, not to mention copper/brass.

Everpure recommends that if you have water that has chloride levels above 80ppm or sulfate levels above 150ppm, you should not use Claris (or any other WAC ion exchange softener), and should consider a filtration solution that will remove or reduce the chloride and sulfates, such as RO with blending or remineralization.

I have a document from Everpure/Pentair that was given to me by Tim Szejbach of Pentair (representing Everpure and Shurflo). They granted permission for me to post it here on HB, so it is available here. The document contains:
  • An example of risky inlet water before and after Claris filtration.
  • A table of corrosion thresholds for various SS alloys by temperature and chloride level.
  • Summary guidelines for when to use Claris. The summary is reproduced below.
Here is the text of the summary from the Everpure/Pentair document on when to use Claris:
  • All weak acid cation (WAC) softening products perform with similar chemistry requirements.
  • Claris (like other WAC products) is great for water with bicarbonate levels above 100 & low chloride and sulfate levels (less than 80ppm and 150ppm respectively).
  • [Claris] Maintains beneficial minerals for quality coffee - Protects equipment from scale formation.
  • Water with high acid risk (high chloride and or sulfate levels) should consider reverse osmosis technology for removal.
  • Note chloride and sulfate limits are based on the stainless steel industry and not on Espresso equipment manufacturers specifications.
Nicholas Lundgaard
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homeburrero
Team HB

#2: Post by homeburrero » Jun 25, 2014, 1:18 pm

Very nice post, Nicholas. Thanks for taking the time to write this up. Also, kudos to Everpure/Pentair for providing the information. The product literature is good, but for someone who wants to see some actual chemistry, that document you imported and linked is outstanding. Nice of them to share it and allow you to provide it here on HB.

AFAIK the Brita filters also use hydrogen ion exchange (I guess is better to say WAC), possibly Pur also, so this info seems relevant to people who use those. Unfortunately it's hard to get this level of information on those filters, probably because coffee water filtration is not a significant part of their markets.
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

post meridiem

#3: Post by post meridiem » Jun 28, 2014, 2:52 pm

Thanks for posting this. If you don't mind helping out a non-chemist here:

I seem to be a borderline case here. Mains water has high sulfates (around 170ppm), but I run the Claris with the highest bypass setting (total water hardness is 120 mg/L / magnesium hardness < 40 mg/L, so I try not to soften it too much). Is there a way to measure if the sulfates put the Claris output into a problematic zone ... i.e., can I just measure Ph, or is there more to it?

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shadowfax

#4: Post by shadowfax » Jun 28, 2014, 3:11 pm

Great question! Personally speaking, I think I would be wary of using the system even if I were borderline. It also makes me wonder how chlorides and sulfates interact, i.e. if you're OK but above 0 for chlorides and borderline for sulfates, does that put you over the cutoff? I will follow up with Tim and see what he has to say about this, as it wasn't addressed in the document they sent me or our conversations.

Do you know your alkalinity (input and output at whatever bypass setting you use)?

I don't know if just measuring the pH is enough, but it is definitely a great first step. I think I would compare the pH from a sample left out for hours (to dissipate the carbonic acid) with the equilibrium pH (calculated from alkalinity). If the pH you measure is dramatically less than the equilibrium pH, I would be pretty concerned. If you're an Everpure customer, I would recommend getting in touch with them—give them your test results and ask for a specific analysis/recommendation. They seem to be happy to help with this, at least the people I have talked to. PM me if you want contact info for the people I know at Everpure.
Nicholas Lundgaard

post meridiem

#5: Post by post meridiem » Jun 28, 2014, 4:18 pm

Thanks, that makes a lot of sense. I'll try to take some initial measurements with aquarium test strips, to get a general sense of where I stand.

Since you know a lot about this stuff: any recommendations for other filtering systems, if the pH ends up being a problem?

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shadowfax

#6: Post by shadowfax » Jun 28, 2014, 6:31 pm

post meridiem wrote:any recommendations for other filtering systems, if the pH ends up being a problem?
Everpure recommends RO with blending/remineralization if you have water with lots of chloride/sulfates. That is probably what La Marzocco or Synesso would suggest as well. I think that's the best option for almost anyone whose water is too hard. Another great alternative is a tank supplying a delivery pump with mixed RO (or distilled) and carbon filtered tap water to achieve a good level of alkalinity, minerals, and pH. I do this, sort of—I've helped a local coffee shop set up and maintain their Everpure MRS-600 (an RO system with blending to adjust TDS), and I fill up my set of 5 gallon tanks for my house from there every month or so. A third option that I would consider is a salt-based ion exchange softener. These remove virtually all Ca/Mg from water, meaning that the water generally won't produce coffee that is as good as if you used water with a modest level of minerality. But you can still produce delicious coffee with them, and they will protect your machine without putting it at any risk for corrosion.

It's very unfortunate that your sulfates are so high, because Claris at its largest bypass setting would probably the most cost-effective, convenient solution for you to get your water right in that ideal range for great coffee with minimal scaling concern.
Nicholas Lundgaard

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Peppersass
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#7: Post by Peppersass » Jun 29, 2014, 3:27 am

shadowfax wrote:A third option that I would consider is a salt-based ion exchange softener. These remove virtually all Ca/Mg from water, meaning that the water generally won't produce coffee that is as good as if you used water with a modest level of minerality. But you can still produce delicious coffee with them, and they will protect your machine without putting it at any risk for corrosion.
Water produced by cation softeners can have plenty of mineral content. What it lacks is carbonate hardness or GH.

In his water FAQ, Jim Schulman gives the results of a blind taste test he performed to compare cation softened water with water that had the "optimum" GH level. Aside from the fact that a single-person blind taste test is still very subjective, there was no more than one point difference between the two samples. That would probably translate to noise in the general population, or even in a room full of expert tasters.

While there have been studies showing that a certain level of mineral content is necessary for optimum extraction, I've not seen any studies that conclusively prove exactly which minerals or ions are responsible for better extraction. It seems that everyone assumes it's the Ca/Mg ions (GH). But since by your own admission one can produce delicious coffee with cation softened water, it must be the case that minerals other than the positive ions making up GH can do a good job with extraction. Jim seems to think so.

I'd like to see a multiple-person blind tasting that compares a variety of coffees made with water consisting of, say, 70 ppm hardness and 100 ppm alkalinity with coffee made from the same water passed through a cation softener (presumably resulting in 0 ppm hardness and 100 ppm alkalinity). And the same test should be repeated with water from multiple locations. It's possible that the exact mineral content of the water, and not just the GH level, could have a significant impact on taste.

Bottom line, when it comes to optimum water composition, there's a lack of scientific and tasting evidence proving that any particular softening system is superior for any given location.

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another_jim
Team HB

#8: Post by another_jim » Jun 29, 2014, 4:01 am

Peppersass wrote:I'd like to see a multiple-person blind tasting that compares a variety of coffees made with water consisting of, say, 70 ppm hardness and 100 ppm alkalinity with coffee made from the same water passed through a cation softener (presumably resulting in 0 ppm hardness and 100 ppm alkalinity).
I'm doing a basic water lecture in late July at the San Francisco CoffeeCon. Previously, I've had people taste various waters (distilled, "drinking water" which is usually around 50 ppm TDS, neutral water, and a high mineral water). As has been usual since the famous bottled water shootout in the 1970s when the NYC water won, the semi-soft drinking water level always wins. The normal comments are that the high mineral waters taste flat, the drinking waters taste crisp and the distilled waters taste weird.

This time, I'm going to try to brew these waters in a coffee, including the high mineral water run through a salt softener.

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.
Jim Schulman

post meridiem

#9: Post by post meridiem » Jun 29, 2014, 9:08 am

shadowfax wrote: It's very unfortunate that your sulfates are so high, because Claris at its largest bypass setting would probably the most cost-effective, convenient solution for you to get your water right in that ideal range for great coffee with minimal scaling concern.
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.

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NelisB

#10: Post by NelisB » Jun 29, 2014, 9:23 am

My opinion is that ion exchange softners tear up the water. I am not going to use them anymore.