Algae: The Green Plague and the Planted Tank

(by Sylphid August 23, 2002)

A three-part article about treating and preventing green algae blooms in planted aquaria.  It’s important to have a full understanding of algae before you take up your weapons—the focus here is on long-term solutions, not bandage patch-jobs.  Having this information at your disposal is the difference between winning one battle and winning the war.  Know thine enemy!

PART I: Introduction to Algae

How does the green slime multiply in size so quickly?  Algaebra!

That was probably a very cheesy way to open an article packed with interesting and applicable facts, but at least now I’ve got your attention.  Nonetheless, I must admit that there’s something particularly cartoon-y about conducting a water change and removing a bucket full of water so green it can be only described as Kickin’ Kiwi-Lime Kool-Aid™.

Pomp and Circumstance:  The Evolutionary Significance of Algae

All joking aside, I have the very deepest respect for algae as a plant—yes, it is a plant.  The first known life on earth—an estimated 3 billion years ago—is alleged to be an ancestor of our modern cyanobacteria, or blue-green algae.  Scientists now believe that it lived on the earth even before there was oxygen or an ozone layer—and that this primitive plant may have been responsible for creating an atmosphere and ozone.  It wasn’t until the presence of this gas shield and protective barrier that other aquatic (and eventually terrestrial) life was possible.  Algae had not only a significant role, but also a significant rule; to this day higher plants aren’t recorded as much older than 500 million years.

The unique qualities of algae are not only an answer to the past, but also a key to the future.  In recent years there has been some experimental energy research with algae farms: when a green algal colony is restricted to a zero-oxygen environment, it uses sunlight and water to produce a pure hydrogen gas as a by-product of its own survival reactions.  Hydrogen gas is a pollution-free fuel, and may one day fill the current role of fossil fuels.   Until recently it could be produced only by fruitlessly using fossil fuels to energize the reactions.  Further research is currently being conducted to use algae efficiently to produce hydrogen gas on a large scale.

The Opportunistic Nature of Algae

Algae’s unique survival skills also make it thrive in our aquariums, although it is frequently unwelcome to.  Simply put, algae will grow anywhere it can whenever it can.  When it can’t grow it can exist as dominant spores, which float around until conditions are more favorable.  It is a fact that very nearly every established aquarium has algae in some form or another.  The goal is to find a balance in the aquarium where algae is present, but not obvious.

 Algae is a plant, albeit a primitive one.  As a plant, algae needs the same three elements in order to thrive and reproduce: (1) The appropriate intensity, spectrum, and day-length of lighting (2) The appropriate micro- and macro-nutrients for growth and cell processes, and (3) A supply of dissolved gas.  As the third item on the list is ever so much more complicated to control, in this article we will place our emphasis on the first two factors.

PART II:     Solutions for Algae

The Importance of Being Explicit

With so much happening in everyday life it’s extremely difficult to remember from day to day what one had for breakfast, never mind how much and what one fed the fish last night!  I strongly encourage any aquarist to keep a written diary detailing regular maintenance schedule, feedings (time, type and quantity), product additions, disease/losses, and test kit/temperature readings.  Bonus points for adding other notes, such as power outages and equipment replacements.  Having a diary is a great reference point for when problems arise; knowing what one did differently is a quicker route to solving the mystery.  A diary is also a fine nagging reminder to keep up-to-date on filter cleanings and media replacements.

The Quick-Fix Over-The-Counter Product

Getting down to business, I don’t deny that there are a number of aquarium products formulated to destroy algae.  Furthermore, I don’t deny that some of them actually work very well.  These products are likely even available at your local fish store—but a few words of caution before you add any ‘quick-fixes’ to your aquarium.  Some of them are algaecides (formulated specifically to inhibit algae) while some are actually herbicides.  This is of particular importance if you are keeping any plants in your tank, as herbicides will melt any aquatic plant indiscriminately.  The more chemicals and formulations that you add to the aquarium, the more complicated the problems become.  Most importantly, quick-fixes address the symptoms in your aquarium but not the source of the problem.  Remember that the source of the problem (whatever it was that allowed the algae to grow) is still present in your aquarium—and you likely aren’t any closer to understanding why the algae bloomed in the first place.

The Long-Term Solution

Putting it simply, the best way to treat algae is to prevent it.  A contradiction?  Perhaps, but as an aquarist you need to put into effect the same principles to both prevent algae and cure your aquarium of it.  However now that you have an algae problem, getting to the bottom of it is the matter at hand.  Through my experiences as an aquarist, I have learned to view an algae outbreak as a proverbial slap in the face directly from my fish, plants and invertebrates united: apparently I haven’t been doing my job in balancing an ecosystem.

In the following section I invite you to consider how your aquarium meets algae’s needs for light, nutrients, and carbon dioxide.  For your convenience, I have this section in the form of a check-list in order to help you with the trouble-shooting.  From here you are well on your way to getting the algae situation under control.

1     Lighting Issues

      Regulate Aquarium Day-Length to No More Than 12 Hours

Excessive lighting is quite frequently the key to encouraging green algae.  Plants, like other living organisms, need both daylight hours and rest hours; plants do most of their growth and repair while the lights are out.  For the benefit of all inhabitants lighting hours in an aquarium should not exceed twelve hours in a twenty-four hour day.  Blasting the aquarium with light for longer can wear everybody out and weaken immune systems, and it certainly doesn’t help any present algae problems.  Between ten and twelve hours is the ideal range for day-length; an electronic timer is a great tool to help you regulate the lighting.  Be sure to program it for the hours when you’re more likely to be at home and viewing the tank.

      Eliminate Any Outside Sources Of Light

Many aquarists have made the mistake of setting the aquarium near a window.  Admittedly, most living quarters have at least one window in every room and in some cases it is impossible to avoid sunlight.  Nevertheless, having an aquarium in the direct sunlight is a recipe for algae disaster.  The excessive light is more likely to benefit algal growth than that of plants.  Drape an opaque towel over the sunny side of the tank and keep the curtains or blinds closed during the daylight hours. This is a good idea even if you don’t have an algae problem.  Remember: prevention is key.

2     Nutrient Issues

      Make Water Changes A Part Of Your Regular Routine

In a natural aquatic environment, water is constantly being diluted and replenished.  This is important to maintain a livable environment for fish, plants, and invertebrates.  In an aquarium, the aquarist needs to artificially simulate this process through partial water changes.  Without the regular replacement of water, wastes and nutrients build up, making conditions ideal for algae to grow and spread.  Removing and replacing 20-25% tank water once per week is enough to replenish the system during normal periods.  During an algae bloom, 10-15% twice a week will help to remove/dilute fuel for algae.

    Keep Up The Gravel Vacuuming

Tank substrate has all sorts of pockets and orifices where food and waste materials can get trapped and start to decay.  Decaying wastes provide a source of food for algae and bacteria pockets.  Often stirring up the substrate or reorganizing the aquarium can yield a sudden increase in algae growth, as the nutrients dissolve again into the circulating water.  Gravel vacuuming should become a regular part of any maintenance schedule, especially if your water filter has biological filtration.  Once or twice a month for all unplanted gravel; twice a year for a good, thorough all-around-and-between-the-plants cleaning.  The water may become cloudy, but with more frequent vacuuming there is less to clean up.  Vacuuming during a water change makes clean-up speedy work, and keeping the gravel detritus-free will also help to keep your tank algae-free.

    Reduce The Volume And Frequency Of Feedings

It is a reality that more fish die from over-feeding than from starvation—my theory is that when fish get hungry enough, one will eventually weaken and die from malnutrition and the other fish will viciously devour the cadaver; hence, nobody is hungry any more.  J  Seriously, though, fish are cold-blooded critters (pun intended) and don’t need as much food as we may think they do.  Keep in mind that any food that you introduce to the tank will decompose, whether it gets eaten or not.  Eventually everything has the potential to become food for algae.  A good start to reducing algae is cutting back on the nutrients that get added to the tank.  Fresh or frozen food is best during a bloom, as it

4   Advanced Algae Solutions

If you’ve tried the aforementioned solutions to no avail, there are some more advanced measures that you may be interested in looking into.  My goal is not to provide specific details here, but to give the more experienced and adventurous aquarists some focus for further research:

     Test Your Source Water For Problem Nutrients

Sometimes the source of the excess nutrients in an aquarium is the source water itself.  Some well (and even some tap) water contains additives like nitrates and phosphates.  Although also consumed by higher plants, both compounds are delicious and nutritious foods and when in abundance are more readily consumed by green algae.  In this case, any number of water changes will not reduce the nutrients in the aquarium.  A great variety of water test kits are available at your local fish store, or you can request a water report from your local water company.  If your water is high in either compound straight out of the tap, algae probably isn’t your only problem.  If your water is full of additives, it is a good idea to research a source for RO (reverse osmosis) water, or even look into obtaining an appropriate system to produce your own.  Be forewarned that RO systems are expensive to purchase.

     Give Your Plants an Advantage with C02 Supplementation

If you’re keeping a heavily-planted tank, if you provide in excess of 2 watts per gallon of tank water, and if you have a regular and carefully-monitored fertilizer regime, you may like to consider embarking on an adventure of C02 gas supplementation.  Where C02 is the limiting factor in plant growth, supplementing this compound will give plants an advantage over algae and the potential to out-compete it for nutrients.

However, I do not recommend C02 gas supplementation for any novice aquarist, as there are particular risks involved.  A single careless mistake can crash an entire aquarium system.  A planted aquarium has an extremely delicate balance between dissolved C02, dissolved carbonates (or KH) and pH.  Before attempting any gas injection, an aquarist would do well to understand this balance.

Summary

Against many obstacles, algae has thrived and come to play a historically significant role in forming Earth’s ecology.  Not unexpectedly, its versatile nature allows it to abound in even the most experienced aquarist’s realm.  Defending an aquarium against algae is not a once-in-a-tank’s-lifetime melee, but an ongoing battle to find balance between the nutrients that are introduced and those that are consumed by flora and fauna.

Regular aquarium maintenance is important in keeping the water clear and the fish visible.   In the long term, it is much less stress to prevent algae outbreaks than treat them: just like the age-old adage of “an ounce of prevention is worth a pound of cure.”  Maintaining a clean tank is a big part of keeping a handle on wastes and nutrients that algae can use to advantage.  Keeping a diary is well-rewarded diligence; an additional bonus is that through intensive knowledge of conditions it becomes much easier to diagnose the source of an algal bloom.  Although using a professionally formulated product may be effective, the temporary effects don’t ensure that algae won’t rear its ugly green head again.

Algae control in the aquarium comes down to two easily-controlled factors: (1) Lighting (2) Nutrients.  Keeping a firm control over both will starve many species of algae out and encourage some species of fish to increase the vegetable intake in their diets.  Incorporating an algae-eating crew into tank populations is a great way to keep controlled algae in check, provided that the aquarium is prepared to keep them long-term.

With your new understanding of the nature of the beast, you have the tools to deal with unwanted algae encounters and to prevent future visits from the Mean Green.  Use your knowledge wisely, Grasshopper.

Other Recommended Reading:

-Sears, Paul L.  and Conlin, Kevin C., “Control of Algae in Planted Aquaria,” Available  on the Internet at http://www.cam.org/~tomlins/algae.html, March 1996.

-Horst, Kaspar, “Everything about Algae,” Aquarium Today, March 1992

-Cell Tech “Algae and Energy,” Available on the Internet at http://www.celltech.com/resources/vt/Algaeenergy.asp, 2002.

Kickin’ Kiwi-Lime Kool-Aid™ is a Trademark of Kraft General Foods
 

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