Algae growth can be a frustrating problem in a freshwater aquarium. Algae spores can be airborne, and can be present in your tap water, making elimination a difficult task. If the algae in your tank are already beyond control, your best bet is to purchase and use an algaecide before trying methods to prevent its growth. Look for an active ingredient called polyethylene dichloride, as it will work the best in this type of situation.

There are many types of freshwater algae. Algae blooms are very common, and are the green algae most often seen in tanks. String algae, hair algae, blue-green algae, blackbeard algae and blanket weed algae are common forms found in freshwater tanks. The recommendations below will help reduce or eliminate these types of algae.

Do not over-feed your fish! The excess food will nourish the algae and allow it to grow even more than it normally would. Additionally, more food means more waste from your fish, providing fertilizer for the algae.

Regular water changes are necessary to help prevent excessive algae growth. 30% water changes, done once every month, will help decrease the waste levels in your water. Using a filter and changing it regularly will also help reduce the algae in your tank. When performing these water changes, clean any artificial plants and decorations. The gravel in the tank should be turned over also, covering up any exposed areas of algae growth as this will kill them. Ideally, cleaning should be done using nothing but hot water and your hands, or a clean scrub brush or algae pad that has absolutely no soap or chemical residue on it.

Exposure to light, especially sunlight, can contribute to the growth of algae. Placement of the aquarium should not be in direct sunlight, or you will be dealing with algae overgrowth that is nearly impossible to control. It is recommended that you turn off the aquarium lights at night, and leave them on for no more than 8 - 10 hours per day.

Adding algae eaters to your tank can be a fun way to help reduce the growth in your tank. Algae eating fish, such as Plecostomus and Otocinclus are both good choices for general algae consumption. The Siamese Flying Fox is a fish that prefers a more specific algae type; thread, string, hair, and beard algae. Chinese Algae Eaters are also helpful, but be aware that these have a tendency to bite at the other fish in the tank sometimes.
Water-dwelling snails of just about any type are great choices to keep algae under control, but they will breed rapidly, so keep this in mind!

Algae eating shrimp are a good choice for an aquarium with peaceful fish. They will help eliminate almost any type of algae in your tank. Check to see if they are compatible with your fish first, because you do not want them to end up as fish food.

Live plants can help control algae also, as the nutrients they need to survive are the same nutrients the algae needs to survive. The plants will dominate the consumption of those nutrients, leaving the algae starving.