What adapter did you get? I just ordered this one: https://www.amazon.com/gp/product/B08F3GL43B/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
It should be here in a few days.
I close mine after every use. I also got my tank new from Amazon for like $75. I'll try to find the hose kit.
Edit: looks like the kit I bought isn't on Amazon anymore, but it looked identical to this: https://www.amazon.com/Cartridges-Adapter-Accessories-Connect-Machine/dp/B08F3GL43B/ref=mp_s_a_1_9?crid=E23SN5B2TVK5&dchild=1&keywords=cga320+to+sodastream+adapter&qid=1634170320&sprefix=cga320+to+so&sr=8-9
Holy crap, tanks have gotten expensive.