New pool owner here (well, renter technically). The landlord started the process of opening the pool but has handed it off to me to complete. Chemical balance is good and tests are all within ideal range, pump is running and maintaining a good prime, but we had some learning curve with vacuuming the pool.

The landlord bought an automatic suction cleaner and instructed us to use it on waste, like a manual cleaner. It quickly dropped the level of the pool below the regulator valve in the skimmer, which introduced air to the system. We learned that lesson quickly, re-primed the pump and waited for the pool to fill to the brim before running the cleaner again, shutting it off each time it neared the regulator valve in the skimmer.

The problem now is that there is air in the filter that I can't figure out how to release. It is an Aqua Pro 24" Sand Filter, and it has a sight glass that is 3/4 full of air. The user manual has only one mention of an air release that points to the outlet fitting identifying it as a "manual air release", does this mean I should attempt to open the outlet fitting while running to let air out? That doesn't seem right to me.

There is no other air release valve or bleeder that I can see. Anyone know how I should attempt to remove air from the filter system?

Thanks in advance!