Removed the boiler from my Gaggia Classic and it was a humbling experience to learn just how much scale can build up even on RO water.
Ultimately wasn’t able to get the boiler looking squeaky even after 2 hours of sitting in descale solution. Is that probably fine? I just rinsed and brushed it until I didn’t see any more visible scale flakes coming off. Flow is back to normal as far as I can tell.
You should consider testing your RO water and replacing the membrane more frequently. There shouldn’t be that much hardness there. My water comes in at about 550ppm and leaves about 20-50 (90% is when you’re “supposed” to replace the membrane from what I remember). I know it’s different than a boiler, but i don’t have scale in my kettle over about 7 years. I recently got a water softener and plumbed my RO into it which should help with longevity (RO was originally invented for desalination).
In the image it looks like there’s some pitting starting, so I’d stop there with the chemistry or see if I can find an alternative.
Good idea on testing the water. I had it installed and just assumed the best.
I think most of the scale must’ve come from the first 2 years when I didn’t use RO water. My kettle doesn’t have any scale in it either and I haven’t had to descale it once since we started using RO water.
Agree with checking membrane but also using just pure RO can be corrosive to metal parts. Wonder if some of this is more corrosion than scale. Checking pH and KH level as and optimizing these often with just a splash of tap water moxedin the reservoir can help and might even make coffee taste better too