The parasite Cryptosporidium was identified in the teaching pool at Northfield Leisure Centre.
Birmingham Community Leisure Trust is anticipating the results for the main pool.
It said it did a variety of tests as an “extra precaution” after the bug was discovered at Cocks Moor Wood pool after a number of swimming became ill.
The pool in Cocks Moor Wood, in Kings Heath, was closed down for four weeks after the discovery of Cryptosporidium. The pool was deep cleaned and immediate action was taken in order to deal with the matter.
The pools at Northfield Leisure Centre closed on 14 June after a different incident and the further testing was done before they were going to reopen.
The trust said: “The pools at the centre on Bristol Road South would remain closed until further notice, but the gym would be open.”
A spokesperson said: “We take the health of our customers extremely seriously and are currently discussing next steps with the council, including the length of time it will take to carry out the necessary measures to eradicate this chlorine resistant bug from the water.”
It said it would reimburse any missed swimming lessons.