My city's water report listed our water as very soft. But I installed a water filter/softener from Chris Coffee, then I measured the results.

Upstream of the filter, the Hach Total Hardness kit reported three drops, or 51.3 mg/L Total Hardness.

Downstream of the filter, my test took one drop, of 17.1 mg/L Total Hardness. Should I remove the water softener?

Your water is soft enough that it should be fine with just a particulates and charcoal filter. It may allow a little limescale buildup, especially if you use the steam wand routinely and don't take care to purge or flush the steam boiler. By using the CCS conventional softener you drop the hardness down to a level where you should be reliably scale free. Some would argue that the higher hardness might produce tastier extractions, but that is debatable. You could try it a while with the softener cartridge removed and see if you think the taste is better.

Thank you very much!

I didn't know that purging and flushing my steam boiler is a routine task. My machine is a Bezzera Duo, a typical dual-boiler machine. The manual mentions back flushing the group head but not purging the steam boiler. Can you give me any advice?

I looked again at the manual and it describes a procedure of turning off the machine and then dispensing water using the hot water tap until no more water comes out. I don't think this completely drains the boiler, but that's what they say. There doesn't appear to be a boiler drain valve besides that.

PeetsFan wrote:I didn't know that purging and flushing my steam boiler is a routine task. My machine is a Bezzera Duo, a typical dual-boiler machine. The manual mentions back flushing the group head but not purging the steam boiler. Can you give me any advice?

There's a recent discussion of that here: Using hot water tap to manage steam boiler water concentration

Fantastic!
I don't think I have anything to worry about. I often preheat my cups using the hot water tap. I know from tests that the steam wand uses extremely little water, so the 4-8 oz of liquid I pull of hot water more than makes up for the steam I use, especially with my very soft water.

I have a cheap TDS meter so I can test the water from my tap, post-filter, and post-boiler. Should be interesting, though my machine is brand new, so I doubt I have any scale at all.