Controlling Aquarium Algae

Fighting the Algae Annoyance

All of us with a fish tank, fresh or saltwater, know the battle that is fought with algae. Many beautiful aquaria have fallen victim of algae overgrowth. Dense algae on walls and structures can be one of the quickest turn offs in an otherwise tranquil aquarium. So how do we eliminate this nautical nuisance? Before we can talk about algae prevention, first we must know thy enemy!

The Low Down on the Green and Brown...
Algae can be found throughout the world relying on water resources from either fresh, brackish or saltwater systems. They can range from microscopic individuals to larger specimen such as seaweeds. Most common types of algae found within our aquariums rely upon photosynthesis to grow. Key elements to their growth include utilizing light, water & carbon dioxide to generate their own food; classifying them as autotrophs. Other nutrients such as nitrogen and phosphorus are also necessary for their survival. Algae can be found in a wide diversity of colors, from black and green to browns and violet.

Though many of our fellow hobbyists view algae as primarily an annoyance, it is important to recognize that many of the aquatic ecosystems that we cherish wouldn’t be possible if not for algae. It forms the basis of freshwater and oceanic food chains supporting the continuing survival of fish and larger aquatic lifeforms. In fact, it is believed that as much as 70% or more of the oxygen we breath was produced by photosynthetic algae. Talk about a breath of fresh air! So let's give some recognition to these autotrophic wonders.

Algae Reduction
While we do acknowledge the significance of algae within our ecosystems, that still doesn’t diminish the fact that you can have too much of a good thing! Besides being aesthetically unpleasing; in a competition of resources, algae can kill freshwater plants and marine corals if their levels go unchecked. It would be nice to completely eliminate algae from our enclosed systems; but the fact is, algae is a perfectly natural part of aquatic systems and cannot be completely eliminated. However, there are many strategies and methods to limit its presence. Let’s explore a few options...

1.) Limit Light
One factor which greatly influences algae growth is the duration of time lights are on over the aquarium. Light is one of the primary ingredients which algae needs in order to produce their food. The proper length of time for lights to be on will be determined based on the aquarium’s type and inhabitants. We recommend anywhere between 8 - 10 hours of light per day. Finding your perfect light timing solution will take a bit of trial and error. This time frame is more of a guideline. Some aquariums, such as heavily planted tanks or reef tanks, may require lights to be on for a greater periods of time.  Please conduct additional research if you have specialty plants or animals to insure you are fulfilling their needs. 

Algae growth in our nano saltwater tank which appeared while fine tuning the lighting of our AI Prime.

It is also preferable to keep aquariums away from windows. Even indirect lighting can lead to algae growth. Our discus aquarium is located opposite of a window and there is noticeable algae growth on the sides of the tank that receives indirect lighting compared to the side that is out of the window’s range. If you desire to keep your aquarium near a window, simply use blinds or curtains during the day to limit indirect lighting. ​

Areas of the tank circled in red receive the most indirect lighting from windows.

2.) Don't Overfeed
Arguably, one of the most exciting events within this hobby is feeding time. Who doesn’t love watching as all of our aquatic inhabitants suddenly give us their undivided attention until they greedily munch on their chow? However, overfeeding does no good for the fish or their watery residence. 

Only feed enough food that your fish can consume in a couple of minutes. Even if your fish are giving you those “hungry eyes”, you must resist! Uneaten food adds additional phosphate and ammonia into the aquarium. Both of which are key components that algae needs to flourish. Speaking of ammonia and phosphates……..

3.) Media Power
Different types of chemical filtration within your aquarium can help to remove some of the excess nitrogenous waste and phosphate. There are many different types of products on the market. In our freshwater aquariums, we typically rely on Seachem Purigen to aid in removing nitrogenous matter and Seachem Phosguard to remove phosphates. Each is placed within a separate media bag and stored within our canister filters. ​

On our saltwater systems we rely on our live rock to assist in the removal of nitrogenous waste through the nitrogen cycle. Additionally, protein skimmers can be used to help remove waste products from fish, invertebrates or uneaten food before it has a chance to breakdown. However, there are chemical products on the market to aid with nitrogenous waste uptake if you are struggling with high ammonia, nitrite or nitrate levels. 

For phosphate removal, we rely on Bulk Reef Supply (BRS) High Capacity - Granular Ferric Oxide (GFO). This brand of GFO can be housed in a media bag within the sump; however, it is most effective housed within a media reactor. For our 12 gallon nano tank, we had to get a little creative and house our media within a small canister filter. You can find more information about the nano build in our article Nano Saltwater Tank Equipment.

4.) Find Some Wingmen
No, I don't mean flying fish! Find some tank inhabitants who will support you in your endeavor of fighting algae. Several fish and invertebrates within both fresh and saltwater systems find algae a tasty meal. For freshwater we recommend otocinclus catfish, bristlenose pleco (aka bushy nose pleco) and Amano Shrimp. For saltwater aquariums look into blennies, tangs, hermit crabs and snails.

Astrea Snail

5.) Add a Little Competition
Algae thrive on the nitrates and phosphates in our tanks, so make them work for it! In other words, add a few competitors for those resources! In freshwater aquariums, plants can be added which will also uptake nitrates and phosphates. This does not leave many nutrients behind for algae to utilize. Additionally, plants can become a stunning component to the aquascape. Saltwater enthusiasts rely on this same methodology within the refugium section of their sumps. Many choose to grow chaeto algae or mangroves as a means to compete with nuisance algae.

6.) Gotta Know When to Give a Little
It is impossible to eliminate all algae from within home aquaria. Instead, consider locations within your aquarium that you are comfortable with its presence. These permissible locations of algae growth will uptake some nitrate and phosphates from the water column. A little algae growth on driftwood or fixed to a stone can provide a freshwater aquarium with a natural aesthetic appeal. Many saltwater aquarists encourage the growth of coralline algae as it can be considered attractive (purple in coloring) and is indicative of an established tank with good water parameters.
 

What if it Isn't Working!
If you have tried the previous 6 tips and are still experiencing algae issues, here are a few other things to consider:

• How old is your tank? Many new aquariums experience a bloom of brown algae (diatoms). The good news is that this tends to diminish over time.
• Check the water you are using for water changes. Depending on your location, tap water can contain high levels of nitrates and phosphates. If your tap water is a source of these algae inducing nutrients or other contaminants, consider switching to RO/DI. For saltwater tanks, RO/DI is STRONGLY recommended. For those interested in building their own RO/DI system you should check out our article, Saltwater Mixing Station. 
• Take a head count. Decaying plant and animal matter can give off nitrates and phosphates into the aquarium. Make sure to check your filters! We once had a cardinal tetra pass and get sucked into one of our Fluval FX6. It resulted in higher than normal nitrate and phosphate readings even following water changes.
• Consider alternative solutions. For extreme algae outbreaks, many have utilized UV filters or algae scrubbers to try and diminish algae appearance.​

Ultimately if you are having issues with extreme algae overgrowth, this is a sign of a nutrient imbalance. You will need to determine what is the source of excess nutrients to eliminate the problem. Solving the problem of algae comes down to process of elimination. With our 12 gallon nano saltwater tank, we experienced an algae issue when we introduced an AI Prime. It took us a little tweaking with the light duration and intensity before we were able to overcome the issue. Don’t get discouraged! Persistence and patience pay off in this hobby!

Keep Krill'in!