Calma's formal professional basketball career began at the age of 26 in the 1986 PBA Open Conference when he, along with several of his national teammates, were absorbed by San Miguel Beer when it rejoined the PBA under the name Magnolia Cheese after a brief period of disbandment.
From 1987 to 1989, San Miguel would win 6 of 7 PBA conference championships, including the coveted Grand Slam in 1989.