Small jellyfish tank with rocky media bacteria filter and foam sediment filter set up about a year, continuously operating and getting periodic water changes and brown algae film wiping. Has not had living jellies in it for 5 months, so I wondered if the bacteria population has remained or has starved. So, on a Thursday we added 1/2 cube of frozen mysis shrimp and students started measuring ammonia, nitrite and nitrate. No ammonia reading on Friday, so I added 1/2 cube more and it went to 1ppm. On Monday there was no Ammonia or Nitrite, and Nitrate was like 5. Since then all readings have been 0. Would you say this tank is cycled and is ready for stocking?