Pools that are indoor or under cover are not exposed to direct sunlight. UV is a main factor in removing chlorine from the pool water. (This is ideal for a Naked System).
With indoor and covered pools it may be necessary to reduce the OXI output by as much as 50% or even more on small indoor pools. It is not critical these are set optimally to begin with and may take some time over different output settings to find the right setting for your pool size, environment and use.