coffeealex but why do you need to refresh the steam boiler for? is it because water that is not circulating is more likely to leave limescale deposits? When you mention the service boiler do you mean the steam boiler? Does a full refresh of the boiler mean opening the hot water tap until x amount of water has come out?

When you steam, the service / steam boiler will leave the minerals behind. The more you steam, the more the minerals as deposits in the boiler. You can draw a small cup after you finish steaming for the day. You can open the hot water from your machine - once a month or every 5-6 weeks, flush all the water out and replace it fresh Pure RO. Every one manages it differently.

coffeealex Furthermore as the key in all of this is the prevention of scaling, what do you use to measure the hardness? Is it test strips or a TDS meter? or other? also when deciding how often to change the filter on OZ what do you use as a guide? ie the change in hardness of the water been extracted after 3 months? 6 months etc In other words looking at whether the filters are still working efficiently? DaveC in one of his articles recommends adding a small amount of bicarbonate of soda to water to improve Ph ie make it more alkaline. Is this because acidic water is more damaging to espresso machines? And is the trade off of in reducing acidity whilst increasing tds slightly a good one in protecting your espresso machine? What would happen if you did not add bicarbonate of soda?

Please get a drop kit from Amazon and measure the GH and KH. Change all the filter when OZ flashes or on the anniversary month of year, which ever comes first. Because, the filters must be changed at least once a year.

With OZ, if running with the mineral filter, you do not need to add anything. Please read the OZ website and talk to them, if you want. Their customer support is excellent.

        coffeealex is it because water that is not circulating is more likely to leave limescale deposits? When you mention the service boiler do you mean the steam boiler? Does a full refresh of the boiler mean opening the hot water tap until x amount of water has come out?

        It’s not “circulation” (as in termosiphon); it’s the fact that you have water with minerals in the boiler, but when you pull steam you are taking pure, distilled water out, and leaving the minerals in.

        Service boiler = steam boiler (but since it can also be used for pulling hot water… it’s not just a ‘steam’ boiler)

        Full refresh = pulling out all water from the service boiler and replacing it with (ideally) low mineralisation/demineralised water. This may involve draining the boiler via siphoning or opening a drain tap if draining via the hot water tap leaves significant amounts of water in the boiler.

        coffeealex what do you use to measure the hardness? Is it test strips or a TDS meter? or other? also when deciding how often to change the filter on OZ what do you use as a guide? ie the change in hardness of the water been extracted after 3 months? 6 months etc In other words looking at whether the filters are still working efficiently? DaveC in one of his articles recommends adding a small amount of bicarbonate of soda to water to improve Ph ie make it more alkaline. Is this because acidic water is more damaging to espresso machines? And is the trade off of in reducing acidity whilst increasing tds slightly a good one in protecting your espresso machine? What would happen if you did not add bicarbonate of soda?

        The only reliable method for measuring hardness is to use a GH (and KH) test kit. Usually in drops. A TDS meter is not particularly useful for a number of reasons, though it may provide an indication, especially if you know what is in the water (i.e. you have remineralised it yourself).

        The duration of any filter - be it OZ, Zerowater, whatever else - depends on how much you use it and on the water you put in. Manufacturers provide instructions on how to assess the state of the filter.

        Bicarbonate - partly used because of corrosion, but largely because it improves the taste of coffee. TDS by itself doesn’t mean much - what the ‘Dissolved Solids’ are is at least as important; water rich in chlorides will corrode, but not necessarily scale. Water rich in calcium or magnesium and (bi)carbonate will scale, but is unlikely to be corrosive. Both may have the same TDS.

        If you don’t add “some” buffering agent (e.g. sodium bicarbonate), your coffee will taste worse and you are more likely to cause corrosion.

        Bear in mind that on the issue of water mineralisation, there are things that are objectively clear and undisputed (e.g. presence of Ca and Mg + carbonates is necessary for scale to form), others that are “challengeable” (e.g. amount of dissolved chlorides that is ‘safe’ for a given material), and others still that are purely subjective: taste (e.g. @Rob1 finds coffee made from water containing magnesium sulphate tasting bad, I don’t).

            LMSC Change all the filter when OZ flashes or on the anniversary month of year, which ever comes first. Because, the filters must be changed at least once a year.

            I thought you changed filters when the performance dropped? The Osmio is pre-programmed to tell you to change the filters around the 12 month anniversary, but that does not mean they do need to be changed. If you only draw 5 litres a week will they need changed even though it tells you?

            https://www.suddencardiacarrestuk.org/2024/02/thank-goodness-for-madeira-cake/

            • LMSC replied to this.

                I’m not sure the OZ is actually programmed to tell to change the filters every 12 months. I’ve owned mine for over 15 months and I’ve yet to see the indication light turn on. It might be because I don’t draw much water or because I drain it and remove the cartridges when I’m away from home for a week or more.

                As TDS remain in the 30-40 range with the remineralisation cartridge, the filters must still be working…

                dfk41 I thought you changed filters when the performance dropped? The Osmio is pre-programmed to tell you to change the filters around the 12 month anniversary, but that does not mean they do need to be changed. If you only draw 5 litres a week will they need changed even though it tells you?

                • I think Osmio recommends changing filters every 6 months or when the filter change flashes.
                • Anniversary filter change is definitely required, if the filter has not been changed before or the filter change flash did not kick-in.
                • Changing filter based on performance loss requires regular (say, monthly) testing of the water. The Osmio Team can advise what their performance yard stick is for changing the filter.
                • If feeding hard water, I think the Osmio Zero might flash filter change regularly. They also recommend descaling the unit.

                Please check the manual or best give them a call. They can guide you on the filter change.

                We feed softened water and changed the filters after 1 year. Unless, the unit flashes, we plan to change the filters once a year. Thx

                    LMSC I just tested the output from my osmio zero with api kit.

                    Filters are 9 months old

                    I feed tap water which is supposedly 220 ppm caco3 hardness according to online (I got 140ppm kh when I tested with the api at one stage)

                    I descaled (it was news to me that this is recommended I was just browsing online and noticed this) at 6 months

                    cleaned through with Milton at 3 and 6 months

                    Today got gh of 44.8 and kh of 40, using 20ml samples from the unit. I guess it’s doing what it should and is fine for the machine then? I will carry on regardless and refresh the steam boiler every few months

                        JahLaza Today got gh of 44.8 and kh of 40, using 20ml samples from the unit. I guess it’s doing what it should and is fine for the machine then? I will carry on regardless and refresh the steam boiler every few months

                        Regular descaling helped you as you are feeding a hard water.

                        I assume the 44.8 mg/l of GH and 40 mg/l of KH are with the mineralisation cartridge and the result you posted is for 5 ml = (number lf drops * 17.9) / 4.

                        I am thinking if the GH is a bit on the higher side. Unless @Rob1 thinks otherwise, your routine is good.

                            LMSC I assume the 44.8 mg/l of GH and 40 mg/l of KH are with the mineralisation cartridge and the result you posted is for 5 ml = (number lf drops * 17.9) / 4.

                            Yep spot on

                              dfk41 I spoke to Mark in detail. The summary of the discussion is given below:

                              1. The filter change sequence is descale —> sanitise —> filter change. The instructions are available online.
                              2. The filter change is a function of water usage. The maintenance light will pop up after 2000L. In cases of low usage, the light won’t pop up; and, their recommendation is change in any case every 6 months.
                              3. They don’t recommend using their unit if the CaCO3 is greater than 250. The 1 and 2 applies in this case.
                              4. If the unit is used on locations where the hardness is > 250 CaCO3, the maintenance light or all lights will flash. This indicates a blockage in the filters. The sequence for this scenario is descale —> Sanitise —> Carbon Filter change —> Reset —> RO Filter —> Reset. The other filters are only need to be changed every 6 months. The users will also have to descale every 2-3 months in this case.

                              All instructions are available online.

                              Edit:

                              I hope I heard 2000L properly.

                                @Rob1

                                The description of the mineralisation filter on their website is as follows:

                                Quick-Change Insertion Filters: Hygiene After-filter antibacterial calcium and magnesium bioceramics, adding a small 10-20 ppm of minerals.

                                Not sure, it clarifies anything without the actual content!

                                As I spoke to Mark from Osmio for another reason, I asked him this. He went quiet, did not confirm if these are from calcium carbonate or organic sources, paused and shared with me his experience at home.

                                He feeds hard water and output from the mineralised RO is 54 mg/l of GH and KH respectively. He doesn’t think this can scale the espresso machine.

                                It is all up in the air! 😊

                                LMSC You can open the hot water from your machine - once a month or every 5-6 weeks, flush all the water out and replace it fresh Pure RO.

                                I am expecting delivery of my Skuma next month, so reading this with interest.

                                I have a Minima and really don’t want to feed it manually so I think doing this would need to be via the main tank. I suppose I could drain the service boiler, then fill the service boiler with the unmineralised RO water and then empty the water tank once the service boiler has filled and fill again with the mineralised RO water. Am I understanding this correctly?

                                    dutchy101 I suppose I could drain the service boiler, then fill the service boiler with the unmineralised RO water and then empty the water tank once the service boiler has filled and fill again with the mineralised RO water. Am I understanding this correctly?

                                    Yes! If there is an internal water tank in Skuma, you need to get that out to provide a pure RO to your minima.

                                    Usually, I don’t bother emptying the unused Pure RO from the espresso machine water tank.

                                    dutchy101 Skuma next month

                                    We are all looking forward to your detailed review mate! 😊

                                          LMSC Yes! If there is an internal water tank in Skuma, you need to get that out to provide a pure RO to your minima.

                                          There’s a function on the machine to dispense pure RO water (without the added minerals) by holding down the button for 2 seconds or so - presumably this will be fine to do?

                                          LMSC Usually, I don’t bother emptying the unused Pure RO from the espresso machine water tank.

                                          Music to my ears - if it tastes OK I suppose there’s no reason to.

                                          Thanks for the help!

                                              JahLaza

                                              Will scale in a service boiler at 125c quite quickly, probably less than a week if you steam for one flat white a day, but brew boiler is fine.

                                              Consider just descaling the service boiler.

                                              How much scale you can get is not possible to calculate as you don’t know what the added alkalinity is from….bioceramics could be silicates or phosphates. In any case, as the pure RO has alkalinity from carbonates, there will be at least some scale potential.

                                                  Rob1 Could he minimise the scaling of the service boiler by refreshing the water in the service boiler ie opening the water tap after steaming or am I missing the point?

                                                  • Rob1 replied to this.

                                                      Rob1 was really hoping the use of osmio would negate the need for any of that but I’ll do what I need to, to keep everything in order! I might just use ro or di water for a few weeks instead of any descaling (I think I might have access to some lab de ionised water) and that might clear things up?

                                                        coffeealex In this case it would be a very frequent and large amount of water to waste.

                                                        @JahLaza but then you’d be making coffee with that too…

                                                            I read these posts and there is a lot of info and some of it can to me at least seem confusing. There are mentions of KH and GH and alkalinity. I thought to ensure i keep my machine at the minimum level of scaling: i do the following

                                                            1. Buy a water hardness kit but not the strips

                                                            2. Start by measuring the hardness of my tap water as a CaCO3 figure with the kit

                                                            3. pour the tap water in to either a skuma or OZ ( leave out the jug versions for this)

                                                            4. extract the water from the RO machine with all filters installed ie mineral filter included

                                                            5. take another reading of the hardness and ensure it is no higher than 80 ( around the 40-80 mgl mark)

                                                            6. Pour that water into the water tank of the espresso machine

                                                            7. if using steaming periodically then flush some water from the hot tap so that the minerals in the service boiler are not accumulating.

                                                            8. Once every 3 months recycle the water in the service boiler with fresh RO water so that very few minerals are left

                                                            9. Alternatively use RO water with no minerals. But in this case add bicarbonate of soda to act as an anti corrosive property in the RO water.

                                                            10. If your machine has stainless steel boilers then there is no need to add bicarbonate of soda as no corrosion will take place but you may still want to add it to improve taste


                                                              I have tried to simplify the procedure so that it keeps scaling to a minimum. Would the above work? or is it over simplified?