Los Angeles hard water, filtration recommendation. - Page 2

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
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#11: Post by homeburrero »

Osanties wrote:Please keep all the geeky details coming that way I put my chemistry PhD to practice...
Always good to hear that someone has an appreciation for the geeky stuff, although I think my level of discussion only requires recalling high school chemistry. I slept through that class, paying attention only when we we were able to derail our teacher and get her to talk about her real passion - raising goats at her home in a nearby mountain village.

Osanties wrote:When it comes to the pHeq, is this also assumed for plumed in machines where water does not equilibrate with air? When I measure the pHs of the water out of the coffee boiler and the steam boiler, I am getting pHs in the 6.8s for the coffee boiler and 7.8s for the steam boiler, I am getting that after heating all the CO2 was removed from the water.
The Puckorius pHeq is a little mysterious to me, and I think was derived from emperical data on cooling towers. It's not as simple as being the pH of water that has been equilibrated with atmospheric CO2, which would tend to be higher than the pHeq.*
Here's an article from the man himself (who passed away back in 2019). As to which is best for your brew boiler calculation, I think that for your brew boiler, your measured pH of 6.8 might be the better number to use in an LSI calculation. That may be moot, considering that the hotter steam boiler ends up with the higher pH and is going to be the one to watch out for potential scale.

Osanties wrote:"The tap water is entering the filter cartridge . First stage particles are removed
by a pre-filter and substances responsible for bad taste and odor (e.g. chlorine) and particular
organic substances are removed by activated carbon.
After calcium ions (Ca2+) are removed by a weak acid cation exchange resin which is
buffered with magnesium ions (Mg2+). They are exchanged vs. H+ and magnesium ions. The buffering of the resin is done to prevent the decrease of the pH down to pH4.
All calcium ions present in the water are removed. This means that not only limescale is
prevented in the equipment but also calcium sulfate deposits (CaSO4, gypsum).
Finally, the water is treated by activated carbon and particles are removed by in a final
filtration step."
That looks like a good summary - I suspect is from Reiner Stannelle? I think he may overstate the calcium removal a little. Some data on the performance of that Mg++ loaded WAC resin can be found in their 2013 patent, especially this table:

In that one it starts out removing 90% of the calcium ion, then plateaus at closer to removing 75% before tailing off as the filter is exhausted. I'm sure they have it tweaked for better performance in the current production, but still would be a stretch to claim 100% removal. And of course this would be at the zero bypass setting.

The buffering would be interesting to know more about, but I'm sure is understandably proprietary. Guessing that it's some form of MgO beads like Corosex, which would do this:
MgO + H₂O → Mg(OH)₂
Mg(OH)₂ + 2H₂CO₃ → Mg(HCO₃)₂ + 2H₂O

Raising the alkalinity and magnesium hardness by small equal amounts and lowering the carbonic acid (thus raising the pH).

* For estimating the pH of water at 25C and at equilibrium with atmospheric CO2 I usually use this handy online calculator: http://www.aqion.onl/show_ph. Using that, given a water with 50 mg/L CaCO3, you expect a pH of 8.2 at 25 ℃. The pHeq at that 50 mg/L alkalinity is much lower, only 7.0.
nínádiishʼnahgo gohwééh náshdlį́į́h


#12: Post by frank828 »

Ciaran wrote: LA water is notoriously variable. It can be anywhere from just bad to insanely bad for an espresso machine. Likewise, WAC cartridges are best when you are dealing with very stable water. So, now you have a filtration system that requires constant monitoring. It's like maintaining an aquarium.
I wanted to second this statement. You will have no idea when and to what your water composition will be changed. It will almost always be somewhere between 250-400 TDS out of the tap though.