1. Home
  2. Blog
  3. Prevention and Control of Nuisance Algae


Prevention and Control of Nuisance Algae

Aqueon Blog Prevention and Control of Nuisance Algae

Every aquarist encounters algae growth no matter how diligent you are about maintaining your aquarium. While its appearance is usually not welcome, algae is nature's way of purifying water and removing pollutants, and it performs a valuable function in the aquarium. Some algae growth in a mature aquarium is normal, however, excessive algae can be a result of problems in water quality and/or maintenance habits. There are many causes for algae growth, and just as many remedies. Understanding what causes algae growth is essential to preventing and controlling it.

Algae Caused by Too Many Nutrients

Algae are aquatic plants in their most basic form, and like all plants they need water, light, minerals and nutrients to grow. In the aquarium the primary nutrients are nitrate and phosphate, which typically come from fish food and fish waste but can also be present in tap water. A build-up of nutrients in the aquarium can be caused by generous feeding, infrequent water changes or filter maintenance, overcrowding, using tap water that has high levels of nitrate and/or phosphate, or a combination of one or more of the above. If you start to see excessive algae growth, test your aquarium and tap water for nitrate and phosphate. Nitrate (NO₃) should be below 10 ppm and phosphate (PO₄) should be below 0.5 ppm.

To keep nitrate and phosphate levels in your aquarium low, avoid having too many fish, feed sparingly and perform regular water changes using nitrate and phosphate free water. To lower high nutrient levels and maintain optimum water quality, clean your filter regularly, use Aqueon Water Treatment Filter Pads, Kent Marine Nitrogen Sponge, Phosphate Sponge, Organic Adsorption Resin, Power-Phos or Reef Carbon. If your tap water has high nutrient levels, use reverse osmosis or deionized water with Aqueon Water Renewal, Kent Marine R/O Right or Liquid R/O Right when doing water changes

Effects of Lighting on Algae

Many people believe that the sole cause of nuisance algae is too much light. Although excessive light is a contributing factor, algae is more common in aquariums with high nutrient levels, especially if there are no live plants. Avoid placing an aquarium where it will receive direct sunlight, even if it's only for a few hours a day. Limit the number of hours the aquarium light is on, especially if you do not keep live plants. A maximum of 6 to 8 hours of light is sufficient in unplanted aquariums, while planted aquariums need 10 to 12 hours of high-quality light per day. Use a timer to provide a consistent photoperiod.

Quality of light is another contributing factor to algae growth. Fluorescent lamps weaken and undergo a change in spectrum called "color shift" as they get older. Since algae are more tolerant of marginal conditions, they tend to prosper under gradually deteriorating light whereas many aquarium plants do not. For best results, fluorescent light bulbs should be changed every 10 to 12 months.

Types of Algae

1. Brown Algae – most brown algae are a form of diatom. They are often seen in newly set up aquariums and will usually die off on their own after the tank cycles. Diatoms use silicates to build their cell walls, so if your tap water contains high silicate levels, use reverse osmosis or deionized water when setting up your aquarium. Place Kent Marine Organic Adsorption Resin or Reef Carbon in your filter to remove nutrients and introduce plecostomus, otocinclus or nerite snails to control brown algae in mature aquariums.

2. Green Algae – there are many types of green algae. Some are soft and easy to remove, while others are hard and can be more tenacious. They grow on the aquarium glass as well as decorations and even the gravel. Snails and algae eating fish help keep many forms of green algae in check. A UV sterilizer will help prevent them from getting started or returning after the aquarium is cleaned. Maintain low nutrients and avoid overfeeding or overstocking your aquarium to prevent outbreaks.

3. Blue-green Algae – these appear as a heavy, dark green film or "slime". They are actually not algae, but rather a form of cyanobacteria. Left unchecked, they can suffocate live plants and even cause harm to fish. Blue-green algae can be removed by siphoning them from the aquarium, but they often quickly return. Several products are available for eliminating blue-green algae that are safe to use in fresh or saltwater aquariums. Cyanobacteria can also be eradicated with anti-biotics, although this method should be used with caution as some anti-biotics can disrupt the balance in your aquarium. For best results, siphon out as much cyanobacteria as possible and remove carbon from the filter before using chemical treatments. Once it has been eliminated, add fresh activated carbon to your filter and do several small water changes.

4. Filamentous Algae – there are many forms of filamentous algae, including hair, string, beard, black brush and thread algae. They are usually caused by a build-up of phosphate in the water and can be seen clinging to plants, driftwood, rocks and other objects. Longer forms can be removed by twirling them around a toothbrush. Siamese algae eaters, mollies, redtail and rainbow sharks, goldfish and Amano shrimp are known to eat them. Shorter varieties can be eradicated using bristlenose and clown plecostomus, otocinclus, nerite snails and dwarf freshwater shrimp. Plant leaves that become covered in filamentous algae should be trimmed out. To prevent filamentous algae outbreaks, feed sparingly, do frequent partial water changes using phosphate-free water and use Kent Marine Phosphate Sponge or Organic Adsorption Resin in your filter.

5. Green Water Blooms – also known as "Pea Soup Syndrome", these suspended algae cause the water to turn bright green and very cloudy. Green water blooms are usually caused by high nitrate and phosphate levels, along with excessive light. Many hobbyists try to solve the problem by doing water changes, but the effects are temporary and the problem quickly returns, often with a vengeance due to the addition of nutrients from tap water. Blacking out the aquarium for several days by covering it with a blanket and turning off the light can be effective, but this is detrimental to live plants and may result in ammonia and nitrite spikes when the bloom suddenly dies off. Diatom filters and UV sterilizers are the most effective cure. Check with your local fish store, as some stores rent these filters for short term use. Chemical algaecides and coagulants also work, but again, sudden algae die-offs can spike ammonia and nitrite levels and some coagulants interfere with the fishes' gills.

Algae and Live Plants

You may have noticed that well-planted aquariums rarely have any algae. That's because aquatic plants remove nutrients from the water and starve out algae. Live plants are one of the most effective ways of preventing algae growth in an aquarium, but it takes more than just one or two to be effective. Live plants work best at preventing algae when the aquarium is heavily planted. Fast growing stem plants like hornwort, wisteria and teardrop Rotala, to name a few, are the most effective at using nutrients and keeping algae at bay.

Live plants need bright, high quality light and do best with the addition of a mineral supplement such as Aqueon Plant Food. They should not be placed in aquariums containing herbivorous fish or those that dig excessively.

Algae Eating Fish

Sometimes, in spite of our best efforts, some algae growth is inevitable. Plecostomus, Otocinclus and Farlowella species, Siamese algae eaters, hill stream loaches and some freshwater sharks feed directly on algae. Bottom feeders like Corydoras catfish and other loach species help reduce nutrient build-up in the water by cleaning up uneaten food and consuming dead plant debris and other organic material that accumulates on the bottom of the aquarium. Use caution when adding plecostomus to planted aquariums, as some species are known to eat broadleaf plants like Amazon swords and Anubias.

Snails for Algae Control

Aquarists often think of snails as a nuisance, largely because of outbreaks of Malaysian trumpet snails (Melanoides tuberculata) and Ramshorn snails (Planorbarius spp). However, several types of freshwater snails are excellent at algae control and will not overrun the aquarium.

1. Mystery or Inca snails (Pomacea spp.) feed directly on algae, uneaten fish food and dead plant material that contribute to nutrient build-up. They are available with black or golden bodies and several shell colors. They will not eat live plants or overrun your aquarium. In fact, they have to leave the water to reproduce, often depositing egg clusters on the underside of the aquarium lid. Due to their size, mystery snails are best kept in aquariums of 15 gallons and larger.

2. Nerite snails (Neritina spp.) have gained in popularity due to their appetite for algae and beautiful shell patterns. There are many types, including some saltwater species, but Tiger and Zebra Nerites are the most stunning and best suited for freshwater aquariums. A secure cover is required as these snails are known to climb out of the aquarium. When introducing them to the aquarium set them with the operculum (opening) down, as they seem to have a difficult time turning themselves over when upside down. Nerite snails are ideal for aquariums 20 gallons or smaller, although they can be placed in any size aquarium.

3. Rabbit snails (Tylomenia spp.) are a recent addition to the aquarium trade from Sulawesi, Indonesia, that are rapidly gaining in popularity due to their active nature, interesting appearance and bright colors. They do best on a sand substrate and prefer temperatures between 80° and 84°F and a pH above 7.5. As with all aquatic snails, a calcium supplement will help maintain healthy shells. They are voracious algae eaters and have very low reproductive rates, so they won't overpopulate your aquarium. They are not known to eat live plants; however, some anecdotal accounts suggest they may be attracted to Java Ferns.

Shrimp for Algae Control

Caridina and Neocaridina shrimp are popular aquarium inhabitants that are often used to control hair and string algae, especially in planted aquariums. While most species are best suited to small aquariums, Amano shrimp (Caridina multidentata) can be kept in most community aquariums.

Filtration to Prevent Algae

Diatom filters and UV sterilizers are very effective at solving green water blooms, but not other forms of algae. Diatom filters trap suspended algae cells on a layer of diatomaceous earth and are removed from the aquarium when the filter is cleaned, thus avoiding ammonia and nitrite spikes. The filter should be checked and re-charged frequently at first as it will clog quickly. UV sterilizers actually kill the algae and do not require any cleaning; however, partial water changes should be done every few days to prevent ammonia and nitrite build-up. Both filters should be left on the aquarium for 7 to 10 days to ensure all algae cells have been removed.

Chemicals for Algae Problems

Chemical algaecides should never be the first choice when dealing with algae problems, as they do not address the original cause of most outbreaks. They can provide a temporary solution, but sooner or later the problem will return if the original cause is not addressed. Proper maintenance, regular water changes, appropriate lighting and sensible stocking and feeding practices are far more effective at preventing and controlling algae growth. That said, sometimes outbreaks occur that do not respond to natural methods of preventing or eradicating them. In those instances, products like Aqueon Algae Remover can help but they should always be used as a last resort. Always follow product directions and remove carbon and other chemical media from your filter before using algae control chemicals.

There are countless articles and videos on how to set up an aquarium, but have you ever thought about how to prepare your house for one? Whether you're bringing home your first aquarium or adding another one to an existing – and growing – collection, here are a few things to consider when getting your home ready for your new arrival:

1. Where to put it?
2. How much does it weigh?
3. Is there an electrical outlet nearby?
4. Other members of the household?

Aquarium Placement in Your Home: Consider Location, Noise and Temperature

First, think about where you want to put your new aquarium. Ideally, it should be located where you spend the majority of your time. After all, an aquarium is a living work of art and you don't want it in an obscure corner that you rarely use. Don't place your tank by the front door or at major intersections in your home as high traffic areas can be stressful to your fish and increase the risk of your tank getting constantly bumped. If you live in a cold climate, avoid placing your aquarium on an outside wall or near an exterior door. You may have to rearrange some furniture or move pictures, shelves or wall hangings. If you're planning on having a taller aquarium, make sure it won't block access to light switches.

Noise is another consideration. Remember that water transmits sound very well and fish are particularly sensitive to strong vibrations. Make sure stereo or entertainment center speakers are positioned so as not to stress your fish. Also, if your new aquarium will be placed near a heating and air conditioning vent make sure they are directed away from it. Avoid putting your aquarium near a fireplace or other heat source that could raise the water temperature above the recommended 76° to 80° F for tropical fish, or 68° to 74° F for goldfish.

Almost all setup guides advise against placing an aquarium near a window, but what if that's the perfect spot for your new tank? The solution can be quite simple. Install adjustable blinds or plan on closing the curtains during the day to block direct sunlight. You can also install background material covered with thin insulation board or cardboard on the back of the tank to prevent algae buildup or overheating from direct sunlight.

How Aquarium Weight Affects Its Placement

Remember that a filled aquarium weighs approximately 10 pounds per gallon. Aquariums of 20 gallons or less can usually be placed on household furniture, providing it's sturdy enough to support them. Larger aquariums should be placed on a stand built specifically for that purpose. Aquariums of 100 gallons or larger should also be placed on a load bearing wall or sturdy flooring, preferably on the ground floor or basement. If you have any concerns about installing a large aquarium on the ground floor consider installing adjustable floor supports in the basement, if possible, to help support the weight. They are inexpensive, easy to install and are available at most home improvement centers. Make sure the floor where your new aquarium will be placed is level, both left to right and front to back. If it isn't, purchase shims to level the stand before placing the aquarium on it.

Consider Your Aquarium's Power Supply/h3>

Make sure there is an electrical outlet near your tank setup. Multi-outlet power centers are fine, but avoid using an extension cord to operate your aquarium equipment. Make sure the electrical circuit can accept the additional load of your new aquarium. This isn't usually a concern with small tanks, but larger aquariums have higher electrical demands. Finally, consider installing a ground fault circuit interrupter (GFCI) on the electrical outlet you'll be using for your new aquarium. 

Regard You Aquarium's New "Roommates"

The most important part of your home is the people living in it. If you have children, help them understand that they should not engage in rough play near the aquarium or hit it with their hands, toys or other objects. Rambunctious dogs and inquisitive cats should be taken into consideration as well. Make sure the aquarium sits on a sturdy stand and purchase a secure cover that can support your cat if he or she jumps on top of it.

By properly preparing your house for a new aquarium, you'll ensure everyone enjoys it, including your fish!

Please join our newsletter, connect with us on Facebook or contact us for more information.

Suggested Products