Extraction Ratio Problem

[Charl]

Hi, I am new to the home barista experience. I am using Breville BES870XL Barita Express.
I was doing much better with my first local coffee ground but now, I just bought stumptown Holler Mountain, roasted at 11/3/2020. My machine insider grinder Set to 4, and side grinder, I even tried #1 (finest today). I am using double size single wall filter. I am using RO water (I know i shouldnt but i like the taste of RO). I filled it with 17gr of grounded coffee. I used Crema brand distributor/leveler & hand tamper. My pressure gauge was at 1 o clock location so pressure was perfect. But when i measured the extract it was 56gr (exactly 2oz) and my extract time was 25 seconds which was also good. Color and cream was also perfect. My coffee puck is quite dry after extraction. But why my extract is almost 3.1x and not 1:1.5 or 1:2 ratio? And most importantly, the coffee is extremely sour. Is it because of Stumptown HM?
I was more successful with my previous coffee beans in terms of taste, but the coffee puck was always little waterish. Thank you for your feedbacks

 

[shadow745]

Thing is every different coffee used (especially for espresso) will require tweaks to maximize the flavor/texture you want/expect. Never had that particular coffee, but notes of citrus are mentioned. Might need a slightly hotter brew temperature, maybe slightly finer grind for a tighter extraction. I know ratios might seem helpful to maintain some consistency, but often those starting out get too caught up in numbers and it can lead to frustration. Going by time, volume and/or ratios is only useful to get you in the ballpark, then rely on taste/texture to really dial it in. Might seem like climbing a mountain when this is all new to you, but for many years I've always said that you never really master espresso as every day there are changing variables that will affect every extraction. Yes you can get to a very consistent point with all that you do, but the coffee itself can/will change day-to-day and slight tweaks must be made to keep things in check. There is no right/wrong way to doing things, just finding what works for you and then repeating that is key. If espresso was easy everybody would do it, but it is challenging and for me worth every bit of time/effort/$ I crank out in pursuit of it.