Filtration and purification are, broadly speaking, the two ways that the water in your spa is kept clean and safe and sparkling.
Water purification is about using chemicals, and in Sundance Spas case, the CLEARRAY UV system, to kill any water born organisms that might otherwise live in the spa water.
Filtration is concerned with removing particles and solids from the spa water.
Filtration is your spas first line of defence against impure water. The filter cartridge will remove anything from a leaf or blade of grass all the way down to absorbing the oils from sun lotions and the natural oils from your skin.
Sundance spas use their own Microclean and Microfibre filters depending on which particular model you own.