Where there is heated water, there will be condensation around your indoor pool!
Chlorine and other chemicals are used in indoor pools and hot tubs to ensure that bacteria do not fester in the water, but that does not prevent live cultures from growing in the droplets and small puddles of water that tend to accumulate outside of the pool, spa or tub.
Each time you get out you take a little bit of water with you. In an indoor room, the water does not simply evaporate. This water has to be wiped up each and every time.
You can remove this water and excessive moisture by using a dehumidifier
If left uncontrolled, bacteria-laden mould will be growing in no time