Nuisance Algae

Algae Basics & Control

The Green Thing (to the tune of “Twinkle, Twinkle, Little Star)

Algae, algae, in my tank
Fighting you, I break the bank.
Swaying in the water so green…
How I wish my tank was clean.
Algae, algae, in my tank,
Phosphates, I alone, can thank.

Hearing the words, “green hair algae”, “Bryopsis”, “Green Valonia (aka Bubble algae)”, and some variations of Caulerpa are enough to send some aquarists begging for mercy.  Thankfully, in the algae world, there are the good, the bad, and the plain ol’ ugly.

Algae falls under three phyla with the red species as Rhodophyta, the green as Chlorophyta, and the brown under Chrysophyta.  Some good species (and readily available in the hobby) of green algae are Chaetomorpha, Halimeda, and Ulva; some bad species are green hair algae, Valonia, Bryopsis, and maiden’s hair.  Although red species are typically more decorative, some may give off noxious toxins to aquarium inhabitants.  I recommend Gracillaria and red Agardhiella as they are beautiful and appetizing food for herbivores.  Also an exception to the “noxious red algae” list is coralline, a somewhat desirable red (or other colored) calcium-based algae.  (Cyanobacteria is just that, a bacteria.  For some, treatment for cyanobacteria is the same as for some pest algae.)  Most brown alga, like Lobophora, are undesirable in the aquarium due to their generally unattractive nature (beauty is in the eye of the beholder…).

Ulva and Red Agardhiella (beneficial macroalgae)

Algae, whether desirable or not, feeds from several chemical sources.  Nitrates, the end product of the nitrification cycle, fuel algae as a food supply.  Nitrates may be found in an impure water supply, caused through excessive feeding or overstocking, or may even result from inadequate filter media.  Phosphates are another trigger for algae outbreaks.  The primary source is usually improperly filtered tap water.  Food for the aquarium inhabitants also generally contains phosphates as well as some commercially available chemicals.  Always check containers to see if the product is phosphate and nitrate free before purchase.  Although some research has shown that diatoms are beneficial in small amounts, generally large “blooms” should be avoided.  Silicates enter the tank through unfiltered tap water, and they may leach from silica based sand (although this topic is heavily debated.)

Problem with Cyanobacteria

Prevention of an algae bloom is ideal and may be accomplished through the use of a quarantine system.  For most corals I prefer to break the coral off the plug or rock, and then seal the remaining rock (not the coral itself) with superglue.  The coral is then placed and kept in quarantine.  Breaking the coral off the base helps prevent any alga that was on the base from getting into the main display.  It is easy for a person selling the coral to just scrub the base before the sale, thus giving the appearance of an algae-free coral.

Many methods are available to deal with the food supply.  Growing macroalgae in a reverse photoperiod refugium, wet skimming, running a remote deep sand bed (RDSB), using phosphate remover media/reactor, and only using reverse osmosis/de-ionized water  are many excellent techniques to control pest algae, and the best results are achieved when applied together.  Certain temperatures, lighting cycles, and other chemical levels (such as copper) may also inhibit the growth of algae but extend beyond the scope of this post.

Unfortunately, the very last method that should be attempted is often the first method attempted by hobbyists.  Manual removal is highly inefficient as it does not target the main source of algae.  It is only a temporary solution.  Although some snails, crabs, etc. eat algae, the spores of the algae are excreted as waste.  These spores then spread throughout the aquarium and regrow.  Removal by hand is time-consuming but is somewhat effective if enough dedication is given.  The algae must be “pinched” off of the rocks and then removed permanently from the aquarium.  Some hobbyists (like me) also cover the algae-infested spot with a mixture of epoxy and/or superglue to prevent regrowth.

Advanced Aquarist Readers.  “Algae Control”.  http://www.advancedaquarist.com/2005/5/tips/view?searchterm=algae 
Fenner, Bob.  “Algae and Their Control in Marine Systems”.  http://www.wetwebmedia.com/algaeconMar.htm
Holmes-Farley, Randy.  “Silica in Reef Aquariums”.  http://www.advancedaquarist.com/issues/jan2003/feature.htm
Paparo, Christopher.  “Algae:  Sometimes both Beautiful and Useful”.  http://www.advancedaquarist.com/2008/2/aafeature3/view?searchterm=algae

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