Wear gloves to remove the cartridge filter and flush away any loose debris with a hose.
Soak your cartridge filter in a bucket containing warm water ad a 5% solution of Cartridge Filter Cleaner and leave overnight.
If the cartridge is not fully submerged beneath the solution in the bucket, then carefully rotate the cartridge into the bucket other-end down
Remove, hose down and allow to dry.
Use a soft brush to remove any remaining particles before returning to service in your hot tub. Always use a spare filter in your hot tub while you filter is being cleaned.