The removal or killing of (blue) algae can be done in a number of ways. One may use UVC, biocides or ozone.
For efficient use of UVC to remove algae water will need to be relatively clear because the UVC light should be able to reach all algae. Often costly measures have to betaken here. Also, the energy consumption of a UVC system is quite high so that the required investment is often high, with a ditto energy costs and replacement lamps
Biocides are chemicals that, as it were poison the algae. So it actually dispenses a quantity of poison to fight the algae but this will leave chemical residues behind.
Ozone can be used to combat all types of algae, including cyanobacteria (blue algae). One has to take into account that an appropriate dosage is used, in practice, a C / Tvalue of 1.5 is adequate. The water does not have to be clear to use ozone and ozone leaves no chemical residues behind. Because of this ozone is an environmentally friendly alternative to combat algae. In many cases, the energy consumption is significantly lower than a UVC system.