Your plum will automatically notify you when your argon is running low, and when it needs replacing. Your argon canister is fully reusable, and you can order replacement canisters directly from Plum or through authorized resellers. To replace the canister, power off your Plum by removing the power cord, and then remove the screw from the argon door on the rear of your Plum. Unscrew the argon canister counter clockwise, and screw the new canister in until its secure. Power your Plum back on, and touch the SETTINGS button and ARGON button to verify the argon canister is now displaying as full.