Yes the UV sterilizer will kill single cell algae and as has been mentioned if you are going this route you MUST also use either a diatom filter or a cannister with a micron cartridge. The reason you MUST do this micron filter is that the sterilizer will kill the algae which if not removed will just decay and fuel the next 'bloom'. However none of this is necessary. Single cell algae require three elements, warm water, excess nutrient in water, sunlight. Our aqauriums are warm because they have to be, without light we cannot enjoy the fish, the key here is control that amount of nutrient in the water. Unless you have live plants which require food the ideal state of the water for the fish is no nitrate, nitrite, or phosphates. I have kept fish for over 25 years inside and out and have never had a 'bloom' in an indoor tank. I'm not saying do not invest in the equipment, I am saying that the equipment can cover poor practices and give the illusion of good water quality. Scott