Some history, i had my Vibiemme Domobar super HX on brita water here in Toronto. I would check for buildup of scale once in a while and had white buildup on the mushroom. We got rid of the brita a while back and went to a Reverse Osmosis under counter system. Today i check the mushroom and find the build up to be black instead...my mushroom doesnt have the chrome plating on it (think it work off over the years..got the machine used..) so this Copper II Oxide? I read that i should be mixing my RO water with either tap or mineral water, could that be the cause? if so in what percentages.

I also got grey flex in the first few ml of water when i turned on my hot water tap (i never use it)

I soaked the mushroom in a little dezcal and it came out clean so i know i got to descale the hx and the boiler
My questions are, is it dangerous to the machine and or my health, and what caused it..

thanks

here is a pic of the mushroom after i removed it.

Have you been using 100% RO water? If so, and if the boiler refill has been working, how? The water level sensor in the boiler depends on some minerals for the water to be slightly conductive to be able to trigger the auto-fill.

I would recommend an Aquarium Pharmaceuticals water test kit to keep an eye on the function of the RO system. You might also think about an inline dual TDS meter for it (as an example, that one is only $30 on eBay, but do a search), and add a mixing valve to add just a bit of pre-RO water to the output to the espresso machine. Either that, or add a calcite cartridge to the line supplying the espresso machine.

The next thing to consider is that I have read from folks who sell RO systems that if running RO water to the ice maker that plastic line should be used as the RO will leach copper and eventually can cause leaks.

If he doesn't comment in this thread, I would send that pic to Stefano (http://www.espressocare.com) and see what he says.

The machine is a pour over, so I'd be just adding mineral or tap water to the RO water I put in the water tank

I've noticed that the parts of the boiler and tubing that are normally exposed to steam turn that same black. I wonder if it's the same sort of effect, from flash boiling.

Anyone know why the boiler components above the water line turn black?

Update,

I did a test with the exact same test kit as in the link, here is what i found.
For GH with RO water it was green on the first drop, so that means less then 17.9 PPM and it took 7 drops on tap water which means its around 125 PPM (norm for my city according to their website)

for KH for both RO and tap water it took one drop to go blue.

I was wondering if i removed the RO membrane from the system would it work? i was hoping to use the three filters before the membrane to filter the water. there is one filter for sediment (rust, sand..etc) one for taste (chlorine..etc) and another for VOC (volatile organic chemicals like benzine and anything else that gets in the water supply from the plant to my house). the system im using is the Watts Premier linked below
https://www.wattspremier.com/products.p...sis-System

I descaled the HX system on my machine but want to make sure i get rid of that black build up..still dont know what it is and kind of worries me for the health of my machine and me...but im also really craving a shot right now too

You are probably near 0,0 on GH and KH. I can only guess at the black stuff... If the RO is leaching copper from the boiler it could be enough to get the water level sensor to work, and the copper is being deposited on the mushroom which is a different material and getting some sort of electrolytic action going... maybe... maybe not. If you were running tap or mineral/spring water in the machine before, the RO could be leaching enough of that out to keep the water level sensor working. To have an autofill system working on RO water, something has to give...

What I did with my softener system was to add a tap on the kitchen sink. If you do that with a Tee, you could put the calcite filter in line with the espresso machine and still have the RO straight for other purposes. But for best taste and life of the machine, you need to add some minerals back into the water. Read Jim Schulman's The Insanely Long Water FAQ.
I wrote two chapters on my water softener system design and installation:
http://www.frcndigital.com/coffee/water1.html
http://www.frcndigital.com/coffee/water2.html

thanks for all the info Randy. What would suggest looks to be for a plumbed in machine, but mine is a pour over tank based model. What i did was just fill the tank with RO water. But now that i know thats a bad idea, is just adding say half the tank with RO water and the other half with plain tap water going to be ok?

Hi Alex, i have a pour-over machine and that is exactly what i do.

I use pure RO water and add some tap water to bring up the mineral content. So far, my mix brings me just below the the "boiler safe" threshold, which means that i should not be accumulating much scale and i still get decent tasting shots. Time will tell if my calculations are correct. My machine is not one year old yet and i am about to check for scale by disassembly of the mushroom.

Remember, pure RO water is also less than ideal for good tasting coffee as there are no minerals to assist the extraction process. What you get is a flat tasting brew.

Water here is Montreal is around 146 mg/l CACO3 (or ppm) hardness and 105 alkalinity. To get to a boiler safe level i've determined i need a 3 to 1 ratio (3 parts RO and 1 part tap). I check the tap water every 6 months and so far it's been pretty stable. Not sure about Toronto...

There are tables you can use to determine what level of hardness you want depending on what kind of temps you are set at (Hx, double boiler and Pstat settings). It's in the insanely long water FAQ. You can read all of it (you will need to read it twice so it sinks in) or skip to the tables. Here's a link:

http://web.archive.org/web/20080526072324/http://www.big-rick.com/coffee/waterfaq.html

Should you have any questions, PM me.

mindless_fool wrote:thanks for all the info Randy. What would suggest looks to be for a plumbed in machine, but mine is a pour over tank based model. What i did was just fill the tank with RO water. But now that i know thats a bad idea, is just adding say half the tank with RO water and the other half with plain tap water going to be ok?

Mine is pour over as well! At least for now. I also have a VBM DS ( lever), and I ran the water system referred to in my two articles above to the machine in preparation for a plumbed in machine that should be here, soon...? Anyway, I terminated the 3/8" JG plumbing line with a 90 degree valve. I currently just use that like a hose nozzle and fill the reservoir that way. Very convenient!

As far as 50/50, it depends on the water... If you can hack into the Watts system, take a line from just in front of the RO membrane cartridge and put in a Tee... Like this:



The valve will allow you to mix just the right amount of filtered tap water in with the RO water. This keeps you from having to run straight tap water in your machine and your hardness test kit will let you adjust it, or get one of those inline TDS meters I referred to above.

Creating that add-on to your system with JG should not be difficult.

Oh, I just went back and reread the OP, and note that I missed that he was currently using RO water.
RO water is corrosive; a simple google search for "reverse osmosis copper corrosion" will give you plenty to consider.