denniskeating wrote:How do you introduce the citric acid to the water without the reservoir tank to put it in?
Add a tee and two stopcocks, one for the mains inlet, one for the bottle of mixture. When it's time to descale, close the inlet from the mains and open the inlet from the bottle, then reverse once complete.
Descaling espresso machines in a nutshell:
Preventative descaling of a single boiler (Rancilio Silvia et al) is trivial - fill the boiler with descaler (or CleanCaf), let it sit a spell, flush the boiler a few times with fresh water. Descaling an HX - not the steam boiler - is even easier. Fill the HX with descaler (citric acid), let it sit a spell, flush a few times with fresh water. Since the HX has less volume then the boiler, it fills and flushes in a jiffy.
Preventative descaling of the steam boiler is a pain because not all machines include a drain tap (e.g., like the Cimbali Junior), forcing you to use the water tap as the drain. The manufacturer does this to save costs. BTW, it's not absolutely necessary to force overfilling by disconnecting the auto-refill. You could also tilt the machine slightly and the autofill should kick in long enough to cover the scale line.
Choosing not to do preventative descaling is unwise. Ask any vendor what is the most common cause of espresso machine failure, commercial or otherwise - they'll all say "scale". If you want to keep your HX espresso machine running well and not spend a lot of time on maintenance, at least run descaler through the HX. It shouldn't take more than 5 minutes once a month.