If you didn't catch anything with the Dawn and the cylinder was empty in 2 days, then you didn't check the leaky connection. Not a chance that you'd miss something that big with any sort of soap.
However, I use kiddie bubble liquid (the type that you use to blow bubbles). It doesn't seem to leave a noticeable film, or discolor anything, which has happened when I mixed dish soap and water and neglected to remove it well.
Snoop is a solid investment in any case.