WHY algae are still present in the tank, despite using OZPOLISH De Algae in the tank

WHY algae are still present in the tank, despite using OZPOLISH De Algae in the tank:

WHY algae are still present in the tank, despite using OZPOLISH De Algae in the tank. OZPOLISH De Algae is a mild algaecide in concentrated form. This means that it is potent to kill most of the algae. However, it won’t be able to prevent the growth of new algae in the tank. To control the growth of new algae, please reduce the photoperiod (light duration) and in the planted tank, if possible, increase the CO2 input. Long duration lighting or direct sunlight will promote the growth for algae. These are the reasons algae in aquariums couldn’t be controlled. Ensure the fish/ shrimp food leftovers are not there. These could be nutrient sources for algae. Alternately, to control the growth of any new algae in an established tank, a deep clean as one-time activity is advised; followed by the weekly applications of OZPOLISH Bio-Cure Standard or OZPOLISH Bio-Cure Advance .