First of all, thanks for pushing this out. I'd been meaning to follow up on this for months as you know, and it's just fallen off my radar. Something happened very recently that changed that. But, first things first.
Peppersass wrote:One theory is that the H+ ion exchange bed in the Claris produces small quantities of HCL (hydrochloric acid) when used with city water containing chloride/chloramine. But I don't have city water -- I have untreated well water. A lab analysis we did 20 years ago shows a tiny amount of chlorine, but no chloride or chloramine.
I think this is probably unrealistic, perhaps downright fanciful. The Claris guys laughed it off easily enough, and so have some other people that I've talked to.
Realistically, I think what explains the low pH entirely is the alkalinity removal. I recall Jim's discussion of the Langelier index in the Water FAQ—alkalinity is directly related to equilibrium pH, and neutral equilibrium pH corresponds to an alkalinity of around 50 ppm. I am not totally sure if that relation holds for water that's treated as Claris water is, so that's a potential unknown there. But it seems clear that when measuring pH at room temperature, the addition of the CO2 to the water by the Claris filter exaggerates the pH reading below the equilibrium pH level that your boiler is seeing.
I'm not sure how big of a deal that is, but to get to the point—the 'problem' with Claris is that you can set it to give you an alkalinity far below 50 ppm with most waters... and you should not do this
. I don't think they adequately warn about how much of a big deal this can be.
A couple of weeks ago I was helping a friend service the groupheads of a couple of La Marzocco 2-group Linea MP (which is a tedious PITA). This Linea was fed by an Everpure Claris filter, and had been in operation for about a year at the time, perhaps less. It was bought brand new. We had originally set this Claris up at a setting of 6 (least alkalinity reduction). When I pulled the grouphead, I was appalled. The whole inside of the group was coated in a copper-red metallic patina (should have been shiny stainless steel). It came off on my fingers when I rubbed it. The copper tubes looked that fuzzy red that you see when you descale copper in citric acid. This was NOT kosher. We eventually discovered that someone had messed with the filter setting and changed it to 0 (maximum alkalinity reduction, with our water this would be about 10-15 ppm alkalinity—!!!
). Needless to say, we immediately changed it back to the 6 setting on the mix valve (which, in Houston, gives ~60ppm alkalinity) and flushed a bit of water through. Everything seems OK now.
I can now say firsthand that Claris can and will damage your espresso machine
if you use it wrong. My advice based on what I see is to forget trying to do anything with Claris other than hitting 50 ppm alkalinity (KH)
or higher on your output water. Don't pay attention to GH, don't even look at TDS. They don't matter. The TDS of the water that corroded the Linea I worked on was easily 200 ppm. Its GH was likely pretty low (<50 ppm), based on my Houston water data, but I didn't have my water testing stuff with me during the repair so we didn't check at the time.
So I'll just say, you've been warned... You should be much more worried about using water with low
alkalinity in your espresso machine than using water with high alkalinity. Scale is reversible to some extent. Corrosion, not so much. It sounds like, in the end, old-school salt-based ion exchange is far and away the safest way to protect your espresso machine from hard water. I think Claris can give some fine water, but if you just get it without testing your water and making sure you get alkalinity right, you are gambling with your espresso machine.