On August 12, 2017, I performed a quick session to compare the color profiles of Dawn Pro (2017) at 20:1 and Dawn Ultra 3x at 30:1. From earlier tests, it was clear that Ultra 3x has more surfactancy than Dawn Pro, but it was unclear how much more. In my July 25 comparison, Ultra 3x at 25:1 created a film a bit thinner than Dawn Pro at 20:1. I felt that I needed to do more comparisons to find an Ultra 3x dilution that was a closer match.
Since Ultra 3x claims to be 1.5 times more powerful than Ultra 2x (which is similar to Dawn Pro), I tried 30:1. I was expecting that the film would be somewhat thicker than Dawn Pro at 20:1 -- meaning that Ultra 3x would have slightly less than 1.5 times the surfactancy of Dawn Pro.
Comparing similarly-sized tubes made with the test solutions, it looks like Ultra 3x is pretty close to 1.5x as surfactant as Dawn Pro. The Ultra 3x 30:1 bubbles were pretty similar to the Dawn Pro 20:1 bubbles in terms of color profile. I'd say that Ultra 3x is a bit less than 1.5 times as surfactant. But 1.5 is pretty close. When substituting Ultra 3x for Dawn Pro, I'd start with 2/3 the amount of Ultra 3x as I would normally use and experiment to see if a little bit more detergent helps.