Clean Tank
Clean tank by gently removing debris on aquarium glass with a sterile (chemical-free) scrub brush. Scrape and scrub the sides of the tank with the clean brush.
Also, do partial water changes to get rid of the tiny algae blooms that are floating in the water.
Filtration System
Do you have an older aquarium? If so, it is highly likely that the out-of-date filtration system needs complete replacement. Bio-Wheel filtration is great to combat algae problems.
In addition, it is necessary to change your filters every 4-6 weeks to maintain a clean tank.
Where is your tank?
Keep your tank away from windows. Sunlight dramatically increases the likelihood of algae overgrowth.
Since algae loves the sun, move it from this light source. Relocate your tank away from the windows.
Algaecides
You can purchase products online or at your local fish store. Algaecides can be very effective in killing algae. However, be sure to implement the other strategies. A product will help but is not a quick fix, by itself. Most brands are comparable to one another. Pick your choice of weapon.
Snails or Algae-Eaters
These aquatic friends can eat algae build-up. Snails seem to be better at cleaning up the tank. Either way, this is a natural way to get rid of algae.
Aquarium Lighting
Do not keep your aquarium lights on - all day and all night. In fact, it is beneficial to keep lighting to a minimum (for example-while feeding fish) when your tank suffers from an overgrowth of algae.
Lamps and lights are just another source that promotes algae growth. This is another excellant way to kill algae in a fish tank.
Plants
It sounds strange, but it’s true. Why have a well-planted tank? A living plant competes for the same resources as algae does. Algae also has a life of its own. Therefore, strong plants will keep algae from growing even more out of control. Amazon Sword is a nice starter plant that only needs moderate care.
Do Not Overfeed
Too much food in the water, leaves excess nutrients. Algae uses these nutrients for its growth. A small pinch of fish food a day is usually good for most average-sized tanks. Decrease or increase amount of food, according to size and number of fish in your tank.