Calibrate your thermometer. When you decreased the bubbles by adjusting to 15, this tells me that your temperature is much higher than you note. These bubbles are the actual carbonation breaking out of solution due to not enough pressure against the beer based on temperature. At retail, this is a technique that draught technicians use to balance the system. Slowly raise the pressure (after quickly opening and closing the faucet)in one pound increments until the bubbles no longer rise or collect. They know that they have achieved equilibrium.
Scott Zuhse, Instructor
Micro Matic Dispense Institute