Green buildup on brass using 70/30 water

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

#1: Post by Liverbird_8 »

Water used
70/30 water
Confirmed by Aquarium test kits

ECM Synchronika (5 months of use)

Upon inspection of my mushroom cylinder and upper brew group valve, I noticed a green buildup on the brass valve and a white compound on the stainless steel mushroom cylinder. There was also a white coating on the spring that surrounds the valve.

I placed the white coated mushroom and spring into a nespresso descaling agent (lactic acid). The white substance immediately flaked off and floated in the solution (no fizz).

The green substance was also removed by the descaling agent but required a bit of wiping down. Unfortunately, I didn't pay attention to the reaction so cannot report if it fizzed.

I'm fairly certain the white compound is limescale. I'm not so sure about the green substance. My initial thought was corrosion or oxidation. However, based on info in this forum, it's dissolution in acid suggests that the green deposits are carbonate. Since my water is free of chlorides, could it be copper carbonate hydroxide?

Although my KH and GH values should not cause scale or corrosion, I'm going to eliminate magnesium and raise the alkalinity while raising the pH. Rpavlis seems to be the best way to achieve this.

Can anyone comment on what may have caused this and if there is anythingi can do to remove buildup that may be in the boilers or piping? Thanks

Before and after pictures

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Team HB

#2: Post by homeburrero »

If you make the '70/30' according to the five senses recipe, you have reasonably good alkalinity, no calcium, and no chloride. The magnesium sulfate is low and should not scale. There is theoretical chance of magnesium hydroxide, which would be a whitish deposit that would readily dissolve in descaler. The green would indicate some form of copper corrosion which could be a copper(II) carbonate hydroxide that would also dissolve in a descaler.

Clearly I really don't know what those deposits are. But I don't think they represent a serious water quality issue nor the need to descale the machine. With respect to copper corrosion you should be better off not descaling and letting the brass parts develop a protective oxide layer.
nínádiishʼnahgo gohwééh náshdlį́į́h

Liverbird_8 (original poster)

#3: Post by Liverbird_8 (original poster) »

Thank you Pat, this is reassuring. I have since switched to RPavlis water and intend to stick with since many have had success with it.