Hoping some of you Cremina veterans can help a relative newbie re: the topic of descaling...yes, I searched and read several deep-dive threads on the topic, but did not find any that answered my questions/concerns entirely.

Background on the machine and how it is used:
-Purchased this machine from Cerini new; took delivery sometime around July 2020
-Machine is used daily for 2-3 shots in the morning. Usually is powered "on" 4-5 hours/day.
-Has been used ONLY with flitered tap water (via a BWT filter pitcher) since day 1. Filter changed in accordance with the "change filter" indicator on pitcher. I am in Natick, MA (west of Boston) FWIW in terms of assessing water issues.
-Until yesterday, I never descaled the machine in the ~9-10 months I've had it.

The scenario prompting my questions/concern:

About a week ago I noticed what appeared to be rust flakes (a brown sediment) floating around in the sight glass / water level indicator while filling the boiler. I reached out to Cerini for guidance and Johnny promptly responded and suggested I descale the machine. Yesterday I performed a descaling using Dezcal (100g w/ 2L of water, per instructions) and let soak in the boiler for 3 hours (per OE descaling instructions). During this time the machine was NOT turned on or heated up.

When I dumped the descaling liquid, it was the color of a weakly brewed black tea -- light brown, with some of those brown "rust" appearance flakes I originally observed.

Per descaling instructions, I performed (initially) 3 fresh water rinses of the boiler to clean out the descaling liquid and any remaining sediment. I continued to get varying levels of those brown rust-looking flakes with each flush (I was dumping into a bowl so I could obersve the water quality/cleanliness). Therefore I continued to flush with fresh water...and probably performed another 15-20 flushes where I filled the boiler and dumped.

By the final flushes, I was still getting modest amounts of the aforementioned brown flakes. I shined a light into the boiler and could see that some (actually, a lot) of the interior surfaces remained coated in that brown looking residue. I could also observe the areas that appeared to be clean metal.

So, my questions:
- Should I be concerned that not all of the brown stuff was removed in descaling?
- Does any of this sound unusual or abnormal for a machine of this age / level of use?
-Any recommendations on what to do in terms of future maintenance/descaling, or water treatment (to avoud this issue moving forward)?

Thanks for any guidance you can provide, and for reading this novel length post.

js

It's possible, if you steam milk, that you've got some residue contaminating the boiler. The proteins and sugars in the dairy can be quite sticky once caramelized by the heat of a boiler and won't come off easily.

Yes, I do steam milk (usually 1x a day) but I always clean/steam purge the wand afterwards...

But I suppose there's a chance it could happen anyway?

It's also possible that you somehow have gotten coffee residue into your boiler, as per this interesting post from the late Dr. Pavlis: La Pavoni Europiccola rust and bad tasting coffee . That post also discusses rust that came from a plain steel nut that had somehow dropped into the boiler.

P.S.

JCS7282 wrote:-Has been used ONLY with flitered tap water (via a BWT filter pitcher) since day 1. Filter changed in accordance with the "change filter" indicator on pitcher. I am in Natick, MA (west of Boston) FWIW in terms of assessing water issues.

I don't think this is related to your brown specs, but a cursory look at your Nantick water report makes me think that might not be the best water solution for you. The water does need to be softened based on that hardness of ~ 90 - 170 ppm. Unfortunately that report does not tell you the alkalinity nor the chloride, but some water in your general area is known to have chloride issues, and your 51 - 190 ppm sodium ion numbers are a pretty good indication that you also have high chloride, which can be a corrosion concern. Your current experience does not look like a corrosion problem yet -- no blue-green deposits and no blue tinge to the descale water. You might be able to call your water utility to get your alkalinity and your chloride numbers. Be sure they know you want to know about chloride ion, which is not the same as chlorine.

If you do have a high chloride problem the only practical way to reduce that is to switch to bottled or formulated water, or to purify your tap with an RO unit. That BWT pitcher filter will reduce calcium hardness a little (good in your case) but may also reduce alkalinity and pH (bad in your case) and will do nothing to reduce the chloride.

( La Marzocco, who years ago identified chloride as a corrosion issue based on experiences in the Cambridge MA area, recommends that chloride ion be below 30 mg/L. For copper/brass boilers and fittings it ideally should be even lower. )

Thanks @ homeburrero for the helpful reply. I need to look into these potential issues.

What a coincidence.. I am also a Cremina user in Natick (feel free to dm me).
Interestingly I had some small amount of rust flakes when I bought mine (very early on after only a month of use).

My issue was probably different: when I dismantled the brew group I discovered that the circlip holding the top gasket (on the inside near the nut on the top of the group) was made of mild steel that was rusting. Bits of rust were getting into the boiler. I have no idea how, since mine was also purchased new.

I ordered the correct stainless one from Cerini, flushed out the boiler (by filling and dumping it into the sink) and it's been problem-free for the last 10 months.

Your issue is more likely water, but it doesn't hurt to do a full group service just to be sure.
As far as water, I found that the big BWT bestmax under-sink filters do better than the pitcher. Even then, I still mostly used distilled water with the third wave water packs.