When you need to empty your spa there are a couple of different options that each depend on your reason for draining the water. The drain valve provides a convenient and inexpensive method to draining your tub as you only need to open the valve and let gravity take care of the rest. Unfortunately this method can take up to two hours to drain a full tub as it relies on the existing plumbing to empty the spa. For a quicker job a submersible pump (which can be purchased relatively cheap at a local hardware store) could be placed inside the spa to empty it in less than 20 minutes.
Emptying your spa is usually done if you either need to change the water (which should be done every couple months) or need to winterize the spa. When changing the water, a submersible pump is the best option as it can drain the spa quickly and effectively. For winterizing we recommend that you use the drain valve (or a combination of both submersible pump and drain valve) as it is much more effective at removing every last trace of water in the system which can freeze during the winter. Each method has its own use, and understanding them can help you take better care of your spa.