Most, if not all, of the above types of hot tubs can be installed indoors as well as outdoors, but several considerations need to be made. Before placing a hot tub indoors, the following things should be considered:
Measurements of the hot tub -- Make sure the hot tub will fit in the space provided with adequate access for entering and exiting the tub safely and performing any cleaning, routine maintenance or repairs. Make sure, as well, that the hot tub will fit through any necessary doorways.
Strength of the installation surface -- Make sure the foundation of the room in which the hot tub will be placed is strong enough to support the immense weight of a filled hot tub. You may need to consult a contractor and/or check city building codes before installation. Also consider installing non-slip surface covers to prevent falls.
Ventilation of the installation room -- Hot tubs create a great deal of heat and moisture that must be vented to prevent the growth of mold and mildew and to prevent disintegration or rotting of walls and floorboards. A nearby window or ventilation system should provide adequate dissipation of moisture and heat.
While hot tubs provide a great deal of enjoyment and relaxation, they also require frequent maintenance to maintain optimal function and performance. At the most basic level, they should be installed in a location where debris from trees, bushes and other sources is not likely to fall into the water. Hot tubs should be covered when not in use and should be emptied, cleaned and refilled every three months (unless otherwise specified) and whenever the water is cloudy or smelly.
To prevent bacterial growth, disinfectants must be used regularly to maintain a proper pH and chlorination level. The pH of a hot tub should be between 7.4 and 7.6, and the Free Available Chlorine (FAC) should be kept at the recommended levels. All levels should be tested with test strips when the spa is filled and twice each week thereafter. Chemicals should be added as needed. It is also important to note that a chlorine smell is not a sufficient indicator of chlorine levels, as it may actually mean that the chlorine levels are low. All necessary chemicals and test strips are available through most hot tub retailers and some mass-market retail stores.
An optional element that may reduce chlorine consumption in most hot tubs is an ozonator, which introduces ozone (a disinfectant) into the hot tub. The two types of ozonators are ultraviolet lamp ozonators and corona discharge ozonators. Ultraviolet lamp ozonators are less expensive, running about $600, but they require more frequent replacement. Corona discharge ozonators cost about $1000 initially, but they last far longer than ultraviolet lamp versions. It is important to keep in mind, however, that hot tubs can run well without an ozonator of any type, so installing one is purely a matter of preference.