Classic: La Basa

Pete, what type of grinder do you have? I too have had this issue with all the arabica coffees I have received from Moustache. I have a Capresso coffee grinder ($80 grinder), and using the finest grind setting no matter the dose or the water my shots extract very fast like you experienced, about 6 seconds and its done. The result..very sour/acidic and bitter. I may not know enough about coffee as you but I have a theory. After doing some research I have found that arabica beans are grown at lower elevations than robusta beans. This gives them a higher lipid content (higher fat percentage), they have about 2-3x more lipids than robust beans. Basically, arabica beans are fattier and robust beans are leaner. This means that if I use the same grind setting for an espresso for robust beans I may get a decent shot, but for arabica beans I will not. This, I believe, according to theory is due to the higher lipid content in arabica beans. Basically the arabica beans are more porous because of the higher lipid content compared to robusta, therefore I need to find a 'finer' grind setting for arabica beans to make a decent shot to compensate for the higher lipid content of the beans. The finer grind will create less 'porousness' (less space) for water to find its way through the arabica grounds when I am extracting a shot. Thats my theory anyway. I plan on giving my theory a try when I can afford a higher quality grinder, but like you, for now, I am not going to be attempting shots with my current equipment with arabica beans.