Post-reverse osmosis water remineralization options for pH control

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

Postby TheMadTamper » Jul 10, 2019, 12:04 pm

So I'm making a ton of changes to the espresso setup, including moving toward a plumbed setup (in progress.) Well, a Flojet driven plumbed setup. Various position/location issues as well as not just trusting it being fully plumbed in after an "ice maker incident" led me to a manual-fill of the bottle from the tap situation to a Flojet bottle. We'll call it "semi-plumbed". Nearly all the convenience, plus a lot of peace of mind by manually filling the reserve on demand. And some minor annoyances when it comes to large flushes.

The fine folks at Chris's have been spending *WAY* too much of their time helping me through all the minutiae of water, and are still helping, but since some of my questions are extending beyond the products they carry, I figure it's not fair to keep pestering them alone about it all, though even still, they're helping where they can! Those guys are rock stars! I can't praise them highly enough! As I shop for a new machine (the poor Duetto needs quite a bit of work, possibly due to water issues over the years that went unknown) it makes me a bit sad to be looking at some machines they don't stock. There's other great dealers, but these guys have been through the trenches supporting me, and it would feel wrong not having them behind the machine. Hard choice there: Buy the wrong machine because it's supported by the right people... Can't get much more praise than actually considering doing that! Those guys are top notch.

So back to water. My tap water, apparently, is saltwater, for no known reason. >60ppm chlorides. That explains a lot, from years of non-stop Duetto problems despite making my own water mixture with some tap mixed back in, to years of tub spigot disintegration from the inside out. Right now I've gone as far as getting a pump-boosted RO set up. Just a generic consumer under-sink one. Sitting in the open. Who needs dinner when there's espresso? It's up, it's running, it's quiet other than the Flojet doing 5 seconds on 5 seconds off, but the refill with the booster is reasonably fast. Waste isn't the best, isn't the worst. It's a kit that's been mentioned in other threads here, including a post about it being used by a Slayer dealer/cafe - iSpring RCC7P-AK. Good kit. But the remin cartridge is giving me some issues. They're a good company with good support, I'm working with them as well, but I have concerns over if dialing it in specifically for the needs of espresso is really in their wheelhouse and I might be going in circles not talking to some of you guys who seem to know a good deal on this stuff!

So right now, I have a feed water with a pH of 7.0-7.5 with an alkalinity of 80. I have not tested what comes straight out of the membrane yet, as I'd have to depressurize the whole thing. However what's coming out of the iSpring FA15 remin is a stratospheric pH.

Feed water:
TDS 170-210ppm
Total Hardness: 180-250ppm
Alk: 80ppm
pH: 7-7.5
Chloride >60ppm
Chlorine .1
Sulfide: 0
Iron: .25ppm

First flush out of FA15 remin after overnight saturation:
TDS: 400ppm
Total Hardness: 5-50ppm
Alk: 40-120
pH: 12.5 (!!!!)
Chloride: 0
Chlorine: 0

Output of FA15 remin after flushing anywhere between 1-6L:
TDS: 30-40
Total Hardness: 0-20ppm
Alk: 40
pH: 10.6-11.2 (!!)


I fear that pH would probably cause even the trace TDS to harden into rock on the element (or just corrode the copper anyway....) Let alone espresso taste (actually, I tried it, it tastes surprisingly good, though a bit...sharp?) Over time as the cartridge ages I'm sure it will drop somewhat. And I'm going to build out a bypass valve specifically so that with *any* remin, I can set it overnight to only send pure RO to the machine so it's not sending 400ppm saturated TDS junk into a boiler for the first refill call on a timer startup, then switch to remin after a line flush on first use. The few ounces of pure RO would easily be corrected by the higher TDS, higher pH water in the boiler from actual running versus trying to get massive mineral buildup out if letting it fill with the saturated stuff.

Still, for whatever reason it's way, way overperforming it's spec, taking a pH of 7.5 -> RO (should LOWER pH), -> remin -> 12.5. Even if I can fix it, it's a 6 month cartridge....trying to dial in a new one every 6 months if it's this much of a variable doesn't sound fun.

So what I'm wondering is, this is a Calcite+Corosex+"mineral stone" cartridge. Would I be better off just replacing it with a generic 10" Calcite filter like CC cells? Not as good mineral mix potential, but maybe more controlled pH without Mg?

Or would I be better off with one of the BWT systems like Bestmax Prem or Bestmin? I'd contacted WLL who contacted BWT, the initial recommendation was Bestmax Prem due to the Mg remin.....but....to me, sending RO water into an IX sounds like a bad plan, or at least an ineffective plan - I may end up with acidic pH again, or without much/any Ca to exchange post-RO, it may do nothing at all. It sounds like it would have been cost effective with the S or V size, but I don't know enough to know if that's a bad recommendation.

Alternatively there's Bestmin. With the FlexHead bypass settings, I could *probably* control the initial flush TDS/GH + pH by just setting the bypass to max. But I don't know if that would be sufficient, or how much water that thing wants to flush. It also has the other problem: In the US, the M size seems to be the only available size. Flushing it daily is out of the question - much too much water in there. Plus it's expensive for a capacity I couldn't use if I tried within 12 months. BUT....If it's what works with the bypass head and larger mineral space...I'd certainly consider it. Nothing else really offers the same kind of single purpose flexibility. Not sure what I'd be getting into there (or if it could end up bringing me back to a scale problem.)

Or could there be other options I'm missing? The more dozens of hours I spend researching, including some of your posts here, the more options and confusion I end up with! This water thing has certainly been an (unwelcome) surprising adventure!

Water is truly the bane of espresso :roll:

ira
Supporter ♡

Postby ira » Jul 10, 2019, 4:08 pm

Saw this today, might be interesting:

https://scanews.coffee/25-magazine/issu ... e-issue-9/

Ira

TheMadTamper

Postby TheMadTamper » Yesterday, 10:02 am

Update: So, apparently it is *not* the remin filter that's boosting the pH. It is boosting pH, but not far outside it's expected norms despite some over-performance. The real issue here is the RO process itself is RAISING the pH, rather than reducing it! Feed water is 7.5 pH or so. What's coming out of the RO with the remin removed is 8.5-10.5! Remin is then simply boosting *that* to 10.5-12.5.

Digging and searching I've found one or two references to the phenomenon, but RO increasing the pH seems like an exceedingly rare phenomenon. And it leaves me with quite a confusing mess to try to control. My current thinking is RO -> DI -> remin.....I can't think of any other way to reduce pH at this point. I just don't know if that'll actually be successful in pH reduction, and/or if there's any problem feeding pure/deionized water into a remin/calcite/corosex system. If it works, I"d hope the DI could bring me back to 6-8, and then remin could bring me back to 7.5-9.5 or so. 9.5 is still on the high side, but a lot more tolerable than double digits. I'd just hope it won't bring me into non-correctable acid territory. And hope similarly that it won't just do nothing.

BTW, Thanks for the link, ira! Interesting read. Doesn't help with the immediate conditions, but it does help understand targets!