Haha just realized it should be 80 bar, my bad. No 50% discount la, maybe 20%? I paid 20 bucks instead. Was doing buoyancy check so was ok, didn't need too much air.
But had to take my regs set-up and test the used tanks 1 by 1

to find one with enough air to use.
Apparently the school doesn't charge the tanks, it's sub-con out to someone. A pick-up will bring the re-charged tanks back to the school