If you have a counter top machine, there is no maintenance that you will do. The machine is designed to drain every time you use it. When you turn it back on it will refill. The electrodes swap after every use so that way no minerals can build up in the electrolysis chamber.
If you have an under counter unit, you still have the reversing of the cathode and anode so you’ll never have to worry about mineral build up in the electrolysis chamber, but there is a 5/16th inch tube that goes from the top of the machine up to the faucet. That tube will have water in it all the time. Typically if you don’t run the acid water through it regularly it can build up some calcium deposits. It is good to either on a weekly basis run the level 4 acidic water through to clean it out. You can also disconnect the tube and run some vinegar through it and let it sit for about 20 minutes once a year.