Detailed Product Description

With the approach of summer time, plankton starts to propagate and
the water turns green. This is because the phytoplankton (Aoko) has
come to grow thick. This phenomenon is called "green water".

The koi is invisible and the oxygen supply shrinks in the green water.
In this case, an ultraviolet sterilization light is to be set up to
protect the koi from this phenomenon.