A spa is a type of hot tub that comes in various sizes. These days people are looking portable spas because you have the option of taking the spa with you when you move and of course if you want some mobility that is also possible.
Stationary spas need a lot more maintenance than the portable ones. These should come with a water treatment chemical kit which will help maintain a level of safety through keeping the water clean. Also, water filters will keep things such as dirt, insects and leaves out.