Thanks guys, I believe the "secret" to running on only 1/4 of a tablet is the soft ink pen spring, I could not get my new D5 to run on the 2.32 PSI output of my aquarium pump Until I did the soft spring mod. It's nice because if I want to go back to "big" fire, it only takes a minute to swap springs.
As I view the water in glass window, it does not even appear to boil like with a full load of Esbit tabs, the water is still and the boiler is not so hot....I must be at a super low simmer temp.
Based on how the engine acts compared to running on 2.32 PSI compressed air, I suspect I am making somewhere around 2 to 3.5 lbs of Steam.