Originally Posted by Calmwaters
If I take out the filter cartridge from the aquarium at home will it not mess up the balance of the aquarium it comes from?
Only if the aquarium at home is new as well. Bacteria gathers on everything in the tank, the glass,gravel,decorations,plants either real or artificial. If what you fear would happen (could in new tank) no one would be able to replace their filter cartridges without the tank crashing. Now if the ten gal at home was using sponge filter for filtration,, then yes ,you would be removing a large portion of bacteria by removing the sponge.
if it will ease your concern,, just use approx. one cup of gravel from one of the tanks at home and place it as described either in the filter compartment of the new tank or, push it into the gravel of new tank. Is impotant to keep the material (gravel) wet in aquarium water (not tapwater) and the tank at work should be set up with filter and heater running before introducing the material and fish. Simply leave the fish in the 2.5 gal until all is ready.