After really heavy use from time to time when you are finding it harder to maintain your water quality you should drain your spa. Use the drain fitting at the base of your spa and the attachment supplied in your warranty pack. Remove the cap, attach the nozzle, click on your hose, twist the base of the fitting anticlockwise and pull on the hose to start the flow. The water will flow through the hose and can be directed to where you want.
Please Note: This video is based on an Oasis spa. Please check with your spa manufacturer for draining instructions as spa drains can vary.