Water, scaling and corrosion...

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

#1: Post by ohmer »

Hello,

I got a new Rocket Mozzafiato R I plan to keep for 10+ years. Rocket doesn't recommend to descale the machine. I would like to avoid scaling (and corrosion) issues. I don't know if this is just me making this hard but this seem complicated.

My city water have a CaCO3 level of 120 mg/L. I understand I can't use that water without treatment, because it will causes scaling issues.

Right now, I'm using Rocket water softener filter that I put in the reservoir. Rocket advice to change it after a year, but maybe I should do it more often just to be sure, like after 6 months? Is it enough to avoid scaling issues with my machine?

The other solution I found is to use distilled water or water filtered with the ZeroWater filter. But this cannot be as easy because I can't use this water without adding some minerals because it will cause corrosion inside the boiler and make the coffee will taste bad. I found some recipes based on Epsom salt and sodium bicarbonate but it's not clear if theses recipes will cause scale or corrosion issues. If this is the only way to give good water to my machine I'll do it, but this make things complicated unfortunately.

I can't plumb my machine right now, so using an inline BWT filter is not a solution for me at the moment. Maybe later when I'll rebuild my kitchen.

What should I do?

Thanks.

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homeburrero
Team HB

#2: Post by homeburrero »

ohmer wrote:Right now, I'm using Rocket water softener filter that I put in the reservoir. Rocket advice to change it after a year, but maybe I should do it more often just to be sure, like after 6 months? Is it enough to avoid scaling issues with my machine?
Yes, the easy and safe option is to just use that rocket tank filter. Your water isn't very hard, but if you want to be extra sure you can replace it every 6 months. That's what Andrew Meo (owner of Rocket) says he does. It would be best to refill your machine with water that has had some charcoal filtration, via the refrigerator filter or a jug filter like Brita. Also, make a point of refilling your reservoir in the evening after you are done pulling coffees that day -- that gives you the long contact time that you need for these pouch filters to work best. I'd advise the Rocket pouch over the BWT pouch unless I knew more about your water. (It is good to know the general hardness (GH), the alkalinity(KH) and the chloride (chloride, not chlorine) when making decisions about water.)
ohmer wrote:I found some recipes based on Epsom salt and sodium bicarbonate but it's not clear if theses recipes will cause scale or corrosion issues. If this is the only way to give good water to my machine I'll do it, but this make things complicated unfortunately.
Most of these will not cause scaling. The best and easiest for a start would be the R Pavlis water* that is frequently discussed on this site. You can use sodium bicarbonate (plain grocery store baking soda) or get some potassium bicarbonate for that. After using and tasting that, then maybe you can play around with a little magnesium sulfate (epsom) and add that if you think it tastes better.


* You'll find tons of R Pavlis water recipes on this site. They all amount to 100mg/L potassium bicarbonate (or 84 mg/L sodium bicarbonate). Here's one easy example if you have a 1 liter bottle for the concentrate and use a 1 gallon container for the final water: Head is spinning! Is there a very simple water recipe?
Pat
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jpreiser

#3: Post by jpreiser »

The water recipes for espresso machines that use distilled/de-ionized(DI) water and either potassium bicarbonate or a combination of Epsom salts and baking soda are meant to be non-corrosive and non-scaling. Along similar lines would be to add a capsule of Third Wave Water to 4L of distilled/DI/RO water. I don't recall the makeup of TWW though.

Another option is to blend some amount of reverse osmosis (RO) or distilled water with filtered tap water but this will require a better understanding of the hardness, alkalinity, pH, and chloride (not chlorine) contents of your tap water to get the mineral levels consistent and correct. While water softeners can reduce hardness (and possibly pH and alkalinity), it won't reduce chloride levels which can cause corrosion; you'd need RO or distillation for that. Also, you'd need to monitor for changes as filters wear.

For a machine with a built-in reservoir, IMO, it's best to go with distilled/DI water and minerals. To make measuring easier, you can mix up concentrates that are then added to a liter/gallon/whatever of distilled/DI water. The concentrate can be made in a 750ml bottle and kept in the refrigerator for quite some time. Then, mix up a batch of brew water as needed.

The simplest recipe would be "rpavlis" water which uses just potassium bicarbonate. Water recommendation is a good starting point for this recipe. Food grade potassium bicarbonate can be purchased at beer/wine homebrew shops or online (Amazon.ca link).

Barista Hustle has a good recipe if you want to try the baking soda/Epsom salts version.

ohmer

#4: Post by ohmer »

How can I test the water hardness after being filtered by the rocket filter? I tried with some strip tests but they measure the same value as unfiltered water. I guess this is because the filter is adding magnesium in exchange.

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homeburrero
Team HB

#5: Post by homeburrero »

ohmer wrote:How can I test the water hardness after being filtered by the rocket filter?
Top up your tank in the evening, then the next morning remove some water from the reservoir. If you use something like a turkey baster be sure to rinse and discard a couple pumps from the reservoir before pulling the water to be tested. Then use a drop titration kit to test the GH and KH of the that water. The best kit for precicely measuring low GH is the Hach HA 71A, but that's a little pricy. The 5B kit is more affordable and should be good enough. The most reasonably priced is the API fishcare GH and KH kit. It's not as good for hardness levels below 20 - 40 mg/L CaCO3 equivalent but may do the job in your case. You can cheat it to get better resolution by using 10 ml samples instead of the 5ml vials that come with the kit. (Use a 10 ml sample with the API kit, and each drop of titrant corresponds to 8.9 mg/L CaCO3 equivalent.)
ohmer wrote:I guess this is because the filter is adding magnesium in exchange.
The Rocket and the Oscar softening pouches are conventional softeners that replace calcium and magnesium ions with sodium ions. They should not change the pH or alkalinity, and won't decrease the TDS meter measurement. They should decrease the GH measurement. They add some sodium but they do not add magnesium.

The BWT in-tank softener is a different animal. It uses a decarbonizing (WAC) resin that softens by replacing calcium and magnesium with protons (Hydrogen ions) which then are neutralized by the bicarbonate in the water, so they lower the pH (i.e., acidify the water) and lower the alkalinity along with the hardness. The lower hardness, alkalinity, and pH all work towards making the water less scale prone. The exchange resin also contains some magnesium in place of hydrogen, so that some of the calcium is replaced by magnesium. To the extent that this happens (which is small, and a little variable) you get a drop in calcium hardness offset by an increase in magnesium hardness, which has no effect on GH, alkalinity, or pH. All together you expect a lower pH, about an equal drop in GH and KH, and some shift from calcium hardness to magnesium hardness. You will expect a small drop in TDS measurement with these.
Pat
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PIXIllate

#6: Post by PIXIllate »

homeburrero wrote:Top up your tank in the evening, then the next morning remove some water from the reservoir. If you use something like a turkey baster be sure to rinse and discard a couple pumps from the reservoir before pulling the water to be tested. Then use a drop titration kit to test the GH and KH of the that water. The best kit for precicely measuring low GH is the Hach HA 71A, but that's a little pricy. The 5B kit is more affordable and should be good enough. The most reasonably priced is the API fishcare GH and KH kit. It's not as good for hardness levels below 20 - 40 mg/L CaCO3 equivalent but may do the job in your case. You can cheat it to get better resolution by using 10 ml samples instead of the 5ml vials that come with the kit. (Use a 10 ml sample with the API kit, and each drop of titrant corresponds to 8.9 mg/L CaCO3 equivalent.)

The Rocket and the Oscar softening pouches are conventional softeners that replace calcium and magnesium ions with sodium ions. They should not change the pH or alkalinity, and won't decrease the TDS meter measurement. They should decrease the GH measurement. They add some sodium but they do not add magnesium.

The BWT in-tank softener is a different animal. It uses a decarbonizing (WAC) resin that softens by replacing calcium and magnesium with protons (Hydrogen ions) which then are neutralized by the bicarbonate in the water, so they lower the pH (i.e., acidify the water) and lower the alkalinity along with the hardness. The lower hardness, alkalinity, and pH all work towards making the water less scale prone. The exchange resin also contains some magnesium in place of hydrogen, so that some of the calcium is replaced by magnesium. To the extent that this happens (which is small, and a little variable) you get a drop in calcium hardness offset by an increase in magnesium hardness, which has no effect on GH, alkalinity, or pH. All together you expect a lower pH, about an equal drop in GH and KH, and some shift from calcium hardness to magnesium hardness. You will expect a small drop in TDS measurement with these.

This is the simplest and most straightforward way I've seen this explained. Thank you.

ohmer

#7: Post by ohmer »

I got an GH/KH aquarium test kit. I'm confused by the results.

When I asked the city what is the water hardness, they told me 120 mg/L. When I tested my tap water, I got:

GH: 80 mg/L (4x20mg)
KH: 60 mg/L (6x10mg)

Then I tested my in-tank water. I refilled the reservoir 12 hours before testing. I expected lower results but the results are the same as unfiltered water!? I wonder if the filter is working now...

Or maybe the test is not accurate? I got this test from Nutrafin: https://www.amazon.ca/gp/product/B00027ZVH8

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homeburrero
Team HB

#8: Post by homeburrero »

That sure looks like the pouch is not softening. Made me so curious that I just ordered a Rocket softener pouch from SCG so that I can give it a trial at home.

Your kit is not highly accurate, but even if the reagents are old I think that the fact that you got a color transition at the same drop count of titrant is pretty convincing that the hardness did not change much. A depleted filter would have that effect, but that seems unlikely with your not very hard water.

Eventually I'll report what I learn on this thread.

P.S. (edit addition)
The Rocket product (filtro osmotic scale reduction) is insufficiently documented by everyone who sells it, but I'm 99% sure that it's a rebranded Bilt O.SCA.R, 90.

The OSCAR one is sold and well documented by Stefano's site: https://www.espressocare.com/products/i ... ener-pouch. It's simply a conventional sodium ion exchange resin with about a 600 grain capacity, treated with silver so as to resist microbial growth. It's not a scale inhibitor, just a conventional softener so we should be able to evaluate it with simple GH test kits.
Pat
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mycatsnameisbernie

#9: Post by mycatsnameisbernie »

I use the BWT pouches. I got the API GH & KH test kit to verify their operation. The pouches reduce my GH from 8 drops (about 130ppm) to 4 drops (about 65ppm).

ohmer

#10: Post by ohmer »

homeburrero wrote:That sure looks like the pouch is not softening. Made me so curious that I just ordered a Rocket softener pouch from SCG so that I can give it a trial at home.

Your kit is not highly accurate, but even if the reagents are old I think that the fact that you got a color transition at the same drop count of titrant is pretty convincing that the hardness did not change much. A depleted filter would have that effect, but that seems unlikely with your not very hard water.

Eventually I'll report what I learn on this thread.
Cool. Let me know the results.
homeburrero wrote:P.S. (edit addition)
The Rocket product (filtro osmotic scale reduction) is insufficiently documented by everyone who sells it, but I'm 99% sure that it's a rebranded Bilt O.SCA.R, 90.

The OSCAR one is sold and well documented by Stefano's site: https://www.espressocare.com/products/i ... ener-pouch. It's simply a conventional sodium ion exchange resin with about a 600 grain capacity, treated with silver so as to resist microbial growth. It's not a scale inhibitor, just a conventional softener so we should be able to evaluate it with simple GH test kits.
I remember seeing something about OSCAR on the rocket filter packaging.