Cyanobacteria (Red/Orange Slime, Blue Green Algae) in Aquariums, as well as related studies in this bacterial plague affecting lakes and other natural bodies of water and how this research can relate to aquariums.
Treatment suggestions for saltwater and freshwater aquariums

QUESTION: What can be done about Blue- green algae (Cyanobacteria) blooms in aquariums?

ANSWER: First, I have dealt with Blue- Green Algae (Cyanobacteria) many times in my Aquarium Maintenance business over the years, and the key is eradication is cutting off and understanding the root cause of this. We have a lot of Blue Green algae problems in the lakes here in Oregon (it is not even a true algae, rather modified bacteria; Cyanobacteria). I understand that the out breaks have differences from aquariums, but there are similarities too. I did research on this subject (including reading the local newspapers about treatment and control in our local lakes). Two points that were made several times are:



[1] Heat; high summer temperatures, and poor in flow and out flow of water seem to induce an outbreak. This also relates to the Redox Potential, I recommend reading more about this here:
THE REDOX POTENTIAL IN AQUARIUMS (& PONDS); and how it relates to proper aquatic health
Fresh water and good Redox potential (-300 mV) seems to play a large role (from my own research and other research articles I have read). In lakes this bloom will usually conside with poor inflow and outflow of water. This also causes a change in trace element content as well as Redox.
This can then be applied to aquariums in that maintaining regular water changes, a GH over 100 ppm (for calcium and trace elements) as well as the correct Redox (UV Sterilization helps here too), will all work towards prevention and eradication of this problem.

[2] Lighting; more research seems to also indicate that the type of light effects the growth of Cyanobacteria. I have noted that many freshwater lake Cyanobacterial outbreaks happen around June and July in more northern latitudes (often around the 45th parallel) which also seems to indicate a lighting factor here as northern latitudes will be more affected by seasonal changes in light than middle latitudes.
Cyanobacteria, utilize light in regions such as the low infrared. These bacteria make use of the unusable light discarded by the plant kingdom, in this case, light outside the PAR range required by plants, which is why Cyanobacteria thrive in lighting conditions that include the more yellow 4000 K and below and why actinic as well as balanced light in the 6400 range.
For this reason it is important to improve your overhead lighting (especially marine aquariums!), in particular the type of output. Get rid of the mid range color output and increase strong daylight with VHO actinic, and SHO daylight or T2 daylight.
In saltwater aquariums, the simple improvement in overhead light, good vacuuming procedures and addition of UV Sterilization (properly installed though) rid the tank of this problem most of the time in my experience.

For further information about lighting, please read this article: “Aquarium Lighting”

[3] Nutrients; the amount of nitrogen based and phosphate nutrients need to be reduced.

As this relates to aquariums, I would increase circulation, clean and vacuum the bottom every other day, cover the aquarium from light for three days, reduce the temperature, consider UV Sterilization to kill free floating spores, and reduce the nutrient level.
Here is an internet source for some of this information I read:
www.spea.indiana.edu/

CYANOBACTERIA BASICS;


Knowing more about this “algae” is important for eradication:

Cyanobacteria are aquatic and photosynthetic, which means, these bacterium live in the water, and can manufacture their own food. Because they are bacteria, they are quite small and usually unicellular, though they often grow in colonies large enough to see.
Blue Green Algae (Cyanobacteria) can look a lot like other true algae, however when it grows on the sides, decorations, and substrate of aquariums it has a much more “slimy” mat appearance and will easily “brush off’ or even come off with a medium to strong current (this is generally not the case for true algae). Cyanobacteria (Blue Green algae) often is not even green, but red or to a lesser degree, brown/ red or even orange. These different color variations are do to Phycoerythrin, a red protein from the light-harvesting phycobiliprotein family which is present in cyanobacteria.

When in free floating form (more common in lakes than aquariums), it will often form a very dense green cloud that may look like paint floating on the water. Some blooms may not affect the appearance of the water. As algae in a Cyanobacterial bloom die, the water may smell bad.
Cyanobacteria are from the phylum Cyanophyta of Bacteria that obtain their energy through photosynthesis. They are often still generally referred to as blue-green algae, although they are actually prokaryotes (organisms without a cell nucleus) like bacteria.
Prokaryotes usually unicellular, although some are capable of forming cell groups called colonies. Individual Blue-Green Algae that make up these colonies will usually act independent of one another. Colonies are formed by organisms that remain attached following cell division, often through the help of a secreted slimy layer that we often see as slimy green mat in our aquariums.
Cyanobacteria are the only known group of organisms that are able to reduce nitrogen and carbon in aerobic conditions. The water-oxidizing photosynthesis is accomplished by coupling the activity of photosystem (protein complexes involved in photosynthesis) PS II and I (Z-scheme; the light-dependent reaction, which converts solar energy into chemical energy). In anaerobic conditions, they are also able to use only PS I — cyclic photophosphorylation — with electron donors other than water (hydrogen sulfide, thiosulphate, or even molecular hydrogen) just like purple photosynthetic bacteria. Cyanobacteria also have the ability to reduce elemental sulfur by anaerobic respiration in the dark. A unique aspect of these organisms is that their photosynthetic electron transport shares the same compartment as the components of respiratory electron transport. It is the thylakoid membrane (the site of the light-dependent reactions of photosynthesis) hosts both respiratory and photosynthetic electron transport, while the plasma membrane contains only components of the respiratory chain.

Cyanobacteria, nitrogen and ammonia:

Since Cyanobacteria have been around before photosynthesizing plants and before there was any free oxygen in the air, it is thought that Cyanobacteria developed the ability to scavenge nitrogen from the atmospheric dinitrogen gas often dissolved in water. Nitrogen is one of the building blocks of amino acids and necessary to living organisms. However, even though nitrogen makes up four-fifths of the atmosphere, it is locked away. Cyanobacteria are able to break apart the molecule of dinitrogen and capture the nitrogen gas via Nitrogenase enzymes. Nitrogenase enzyme molecules are very large, complex enzymes, built of two twisted and balled-up proteins, that combine and recombine to convert a molecule of N2 to two molecules of usable ammonia, NH3. Though Nitrogenase enzymes enable conversion of atmospheric nitrogen so that it can be employed in life processes, it is ineffective in the presence of oxygen. To protect the Nitrogenase from oxygen, many nitrogen-capturing Cyanobacteria (usually of the filamentous variety) have developed special nitrogen-fixing cells called Heterocysts encased in thickened cell walls. Because of this ability, low nitrate levels are generally not the key to stopping this plague.

Here is reference site about bacteriolgy that I found both interesting and useful:
THE DIVERSITY OF METABOLISM IN PROCARYOTES

TREATMENT (eradication);


With some of the above information in hand, one can now make more informed choices about how to eradicate Cyanobacteria.

*30% water change (or more) using a Gravel Vacuum (especially to remove nitrogenous waste producing mulm than often accumulates under rocks or UGF plates). Also check canister filters and wet dry filters in particular for organic mulm buildup that will eventually add nutrients to the water column. This cuts off one source of nutrition.
Removing hydrogen sulfate producing anaerobic bacteria in freshwater is important as well, so make sure and vacuum all the dead spots. Along this line of thought, removing sand and replacing with gravel has helped in aquariums I have monitored with BG algae.

*Improve aquarium lighting to include more actinic and daylight and less of the yellow/green visible light. Lights around 6400 K are best, especially high output lamps, while standard incandescent lamps will allow more Cyanobacteria growth.
Consider T2 daylight lights and fixtures or Compact Fluorescent lamps that easily fit into most standard incandescent fixtures

*Electrolytes and minor elements such as magnesium and calcium Wonder Shells are useful, this is very important

*Add a UV Sterilizer (Very effective but not always cost effective for small aquariums, but is worth mentioning, not just for sterilization, but for Redox which plays a role in controlling bacterial BG algae). The key for UV Sterilization to be effective is for proper installation with a well designed unit, not a poorly designed unit (often sold by some retailers). Make sure your flow does not exceed 30 gph per watt (less is better) and that you have a good flow pattern in your aquarium and finally that you regularly clean any areas of BG algae build up to dislodge it.

*In marine aquariums the addition of Mexican Dwarf Hermit Crabs (Clibanarius digueti) can vastly cut down on Cyanobacteria growth. These crabs are extremely efficient.
Here is a quote: “I had several rocks which had Cyanobacteria red slime algae covering them from the old system. The morning after adding the crabs I witnessed "Herds" of about 6 or 7 crabs each that would concentrate on a rock at a time, totally eliminating the Cyanobacteria I have never heard of a cyanobacteria eating critter like this and it seems they actually prefer it! A week later, my tank was almost completely free of red slime”. For more about these crabs, please read this out side article resource: “Natural Red Slime Algae Control for Reef Aquariums”

*Improve the Redox Potential; this is often missed, however this is an important part of the equation. For more, please read this article:
THE REDOX POTENTIAL IN AQUARIUMS (& PONDS); and how it relates to proper aquatic health

*Cut back on nutrients in the water column by the use of RO instead of tap water in marine aquariums and in ALL aquariums cut back on feeding and improve food quality (No TetraMin). Better choices: Ocean Nutrition, HBH, Spirulina 20 just to name a few. This again will cut back on nutrients.
You want to aim for less ammonia (not necessarily nitrates due to the properties of Cyanobacteria), which is the result of poorly digested food

*Increase circulation and dissolved oxygen. These Prokaryote Bacteria do not do as well in a well oxygenated/ circulated environment (remember my points about the lakes).

*Temperature; although this by itself will not make much difference, lowering your aquariums temperature (below 76 F) has been shown to help when part of an over all plan for BG algae removal or prevention.

*Medication; Copper at a level of 15 to 20 ppm is effective in inhibiting effective photosynthesis. Erythromycin has shown to be effective here as well.

*Lighting; turning off lights and/or covering the tank, although this is often recommended for the eradication of Cyanobacteria, this is often not effective and the BG algae bounces right back. The reason is as stated above that Cyanobacteria have the ability to reduce elemental sulfur by anaerobic respiration in the dark.

Better is to have the CORRECT lighting such as higher output 6400K lights.

CYANOBACTERIA IN MARINE AQUARIUMS:

In saltwater aquariums, Cyanobacteria are often red and appear as a red slime, thus the term “Red Slime Algae” used to describe this in marine aquariums. This NOT to be confused with coralline algae which is indicative of a healthy marine aquarium (see this article about marine chemistry necessary for the growth of coralline algae: “Aquarium Saltwater (marine) Basics”
In Marine Aquariums dissolved organic carbon is the result of anything organic that has died off and gets decomposed by bacteria. Dissolved organics are a food source of the bacterial side of the Cyanobacteria (Red Slime Algae). Sources of this dissolved carbon can include dead algae, bacteria, digested or uneaten food, metabolic waste, and some organic aquarium additives.
Aquarium additives, such as alkalinity controllers, contain bicarbonates. Bicarbonates convert into CO2, thus adding to the carbon levels. This also explains why Cyanobacteria are a common problem in saltwater aquariums.
As with Freshwater, limiting dissolved organic carbon can help, but the bacteria-algae is capable of consuming all the carbon needed derived from CO2. It is therefore important, especially for marine aquariums, to ensure a proper gas-off by water movement and adjustments of water flow. The more oxygen created, the better the degassing effect.
Filtration such as a well maintained (frequently rinsed) filter can reduce organics and thus carbon. Skimmers are effective tools, but need to be maintained frequently. The Berlin Method that combines mud filtration or a Refugium is also beneficial along with UV Sterilization.

Further Reading/References:
http://www.ucmp.berkeley.edu/bacteria/cyanointro.html
http://tolweb.org/Cyanobacteria/2290/2006.03.10
http://www-cyanosite.bio.purdue.edu/taxon77.html


Carl
Last updated: 4/15/08