Not answering your question directly, but I have been using the Durgol Swiss Espresso descaler very successfully in my wife's Gaggia Classic. It cleans quickly and rinses out easily. Absolutely no after taste. I clean the shower separately with a painters brush and mild detergent using light swirling motion. The shower needs to be cleaned much more frequently than the machine. It seems the the shower needs cleaning every 40 shots or so, whereas the machine will depend on your water condition; I get several hundred shots before decaling.