Friday, October 11, 2013

Every year our pond gets plagued with string and hair algae. We check the pond several times a year and every time we check, the parameters of the pond show that we have no nitrates, and everything is within its limits. Could you please tell us why this nuisance algae keeps coming back year after year in our pond?


Every year our pond gets plagued with string and hair algae. We check the pond several times a year and every time we check, the parameters of the pond show that we have no nitrates, and everything is within its limits. Could you please tell us why this nuisance algae keeps coming back year after year in our pond?


Cyanobacteria; these polyonymous bacteria are very misunderstood Blue-green algae’s, known by many hobbyists as blanket weed, string and/or hair algae (for all practical purposes the terms blanket weed, string algae, Blue-green algae or hair algae are a metonymy meant for Cyanobacteria) will eventually plague everybody’s pond at some time. It is often difficult to overcome because the pond hobbyists failed to understand its cycle and the exigency of the situation, so they wait far too long to intervene. Its long, soft, and hair-like strands can swiftly cover an extensive area. Not only does it become independent of bulk water nutrients once established, trap detritus and/or debris can add further nutrients to the water column. This algae, is bacteria, which many botanists classify as Blue-green algae, this particular bacteria belonging to the kingdom Prokaryote which means “before the nucleus,” and all other algae classified in the kingdom Protista. 

The cells of Blue-green algae form strands and lack a distinct nucleus, which contains no DNA inside. Instead, their DNA is simply floating around freely in the cells, not contained in a discrete organelle. Bacterial DNA is primary contained in chromosomes, just like ours, although structures called plasmids contain bacterial DNA, as well. Unlike animals, bacterial cells also have a cell wall, which differs from that of plants in the types of proteins that make up the cell wall. 

Cyanobacteria contain chlorophyll a, which gives it a greenish color, but they also contain blue and/ or red lipid soluble pigments (coloring matter). Many species can take nitrogen from the air, convert it into compounds called nitrates, and therefore help fertilized soil and water. Blue-green algae’s can use low light levels, contrary to what most hobbyists believe. Most Blue-green algae reproduce only by cell division and tiny spores packets called “sporangia” that form along its hair-like strands. When these packages mature, they burst open and release spores that settle and grow into “gametophytes,” which look like small green bubbles. When these bubbles mature, they released male or female cells that eventually unite and form a “zygote,” which is the base unit for the growth of a new structure of hair algae. 

Many hobbyists are accustomed to Blue-green algae forming a slippery dark coating over rocks and boulders on their waterfalls. Eutrophication of pond water has a large part in the growth rate of cyanobacteria. Unlike our ponds that may become eutrophic in one or two seasons, lakes, and ponds naturally become eutrophic over hundreds or thousands of years. The actual cause of warping the ecology of a pond and accelerating it into eutrophication are humans, this activity is called cultural eutrophication. Therefore, in a way, we have no one else to blame but ourselves, when it comes to hair alga problems. 

 Our ponds support a natural cycle of life processes. The bacteria of decay breakdown the waste of fish and other organisms, releasing such nutrients as carbon dioxide, nitrate, and phosphate. The hobbyists upset this natural balance when he or she adds too many animals to the ponds bulk water and by overfeeding with foods that contains phosphates. Many of the excess of nutrients that enters the bulk water and causes problems come from the filtration system itself. Often, pond hobbyists wonder why these growths persist when their nitrate and/or phosphates levels appear to be very low to nonexistent. They exist because once established the cyanobacteria growth need little or no nutrients from the bulk water. They simply make their own nitrogen and phosphate needs in and below their base structures with the hobbyists providing little else but a preferred environment with which to live. In addition, initial growth is usually in an area that are next to a small amount of nutrients found on or in rock crevices and gravel bottoms, or on the sides of the pond walls where nutrients are abundant in bulk water. Therefore, it is wiser to have nutrient users initially, than nutrient sources and no means to dispose of them.  

However, this is not as easy as it sounds. Cyanobacteria grows best in nutrient rich systems, and where very low or no flow areas exists in the pond. Spores are much like detritus (particulate organic carbon [POC], organic and inorganic particles), and end up where the flow is the slowest. 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 photosystems (protein complexes involved in photosynthesis) PS-II and PS-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, thiosulfate, 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 hyracoid 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. 

It is also a fact that Cyanobacteria have developed the ability to scavenge nitrogen from the atmospheric dinitrogen (N2) gas often dissolved in water. This nitrogen is made from the Biocenosis clarification baskets in the Anoxic filtration system from Dissimulative Denitrification. This is one reason that the filtration system may become full of Cyanobacteria but the ponds main body stays clear of such. Nitrogen is one of the building blocks of amino acids and necessary to living organisms. However, even though nitrogen makes up 78% of the atmosphere, it is locked away. This is also one way to tell if your Anoxic filter is working properly and making N2 before the filter can eradicate the cyanobacteria. 

Cyanobacteria are able to break apart the molecule of dinitrogen and capture the nitrogen gas by way of Nitrogenous enzymes. Nitrogenous enzyme molecules are very large, complex enzymes, built of two twisted and balled-up proteins, which combine and recombine to convert a molecule of N2 to two molecules of usable ammonia (NH3). Though Nitrogenous 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 Nitrogenous from oxygen, many nitrogen-capturing Cyanobacteria (usually of the filamentous variety) have developed special nitrogen-fixing cells called Heterocyst encased in thickened cell walls. Because of this ability, low nitrate levels are generally not the key to stopping this plague. Removing hydrogen sulfate producing obligatory anaerobic bacteria in ponds is very important as well; this is more pragmatic with rocks and stone at the bottom of ponds sitting on the pond liner surface. There is also a correlation between setting up a pond this way and that of Blue Green alga plagues. 

The Anoxic Filtration System designed specifically to deal with cyanobacteria especially in early spring and late fall when nutrients are at their peak. Because the water is defused in the filtration system where the flow rates are slower over a wider mass, will then act as a massive settlement chamber for detritus and the spores of cyanobacteria. If the filtration system is set up correctly these nutrients rich waters will never mix with the ponds main bulk water. As hair algae and string algae begin to form in the filtration system, the system will now begin to work overtime by (increasing the number of bacteria related to nutrients) eradicate the nutrients that are now in the system. These particular filtration systems will get loaded full of hair algae, but the main pond stays algae free and crystal-clear. When the filtration waters become nutrient poor, the cyanobacteria will then die off. 

In the more commonly used filtration systems which water is being forced through the filter medium, nutrient runoff, redistributes the waste and further adds to nutrient accumulation mixing with bulk water and everything in the pond becomes covered with hair and string algae. The nutrients are not being contained in any one particular place; therefore, the entire pond becomes a nutrient rich environment for cyanobacteria. For the hobbyists this means doing whatever it takes to maintain phosphate below 0.015- ppm and nitrates below 15-ppm. Since each pond is as different as Koi are, it is difficult to say just what needs to be corrected and how. Many pond-hobbyists to eradicate hair algae will want to use antibiotics, but this should be avoided. Most antibiotics interfere with proteins in some way, including the structural and transportation molecules in the cell wall, and enzymes, which are responsible for the breakdown, synthesis, and transportation of substances through the cell. The use of antibiotics such as

Tetracycline, Penicillin, or Erythromycin sulfate may eradicate these unwanted algae (aka: Cyanobacteria) the first time, but further problem blooms may persistently plague the pond, because of the bacteria mutating, creating a bacterium into a superbug and therefore become less susceptible to the antibiotics. You would be better off trying to get to the root of the problem than to be administering antibiotics into the pond. In addition, remember that antibiotics negatively affect biological filtration and can disrupt or even wipeout the biological filter in our ponds, depending on the condition in the filter and how much antibiotic were used. 

Here are some helpful hints on trying to overcome Blue-Green alga plagues:

1. Electrolytes and minor trace elements such as magnesium and calcium are useful. This cannot be over emphasized enough to the hobbyist.

2. Adding an Ultraviolet Sterilizer (Very effective, not just for sterilization, but for Redox which plays a role in controlling bacterial Blue Green algae). The key for any UV unit to be effective is for proper installation of such, with a well-designed unit, not a poorly designed unit (often made by some manufacturers with cheap ineffective UV lamps). Make sure your flow does not exceed 30-gph per watt (less is better) and that you have a good flow pattern in your pond. This means trying to avoid any and all dead spots in the pond. Sometimes adding air-stones and/ or more water movement by pumps will do the trick. Do not think that a small 300-gph pump is going to move enough water to make a difference in all but the smallest of aquatic environments, it won’t. Buy yourself one or two of the Laguna Max-Flo 2900 pumps. These pumps will move 2900-gph and only use about 130 watts of electricity. Increasing circulation and dissolved oxygen is extremely important. These Prokaryote Bacteria do not do as well in a well oxygenated and/or circulated environment. 

3. Improving the Redox Potential, this is often missed; however this is an important part of the equation. 

4. Cutback on feedings and improve the quality of food you feed your fish. This again will cut back on excessive 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. 

5. Cutting back on the amount of sunlight that the pond receives a day, although this is often recommended for the eradication of Cyanobacteria, this is often not effective, and the Blue- Green alga will overcome such an impediment. The reason is as stated above that Cyanobacteria have the ability to reduce elemental sulfur by anaerobic respiration in the dark. 

6. As with all ponds, 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, to ensure a proper gas-off by water movement and adjustments of water flow. The more oxygen created, the better the degassing effect. Pond 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. 

7. Pre-filtration such as a well maintained (frequently rinsed) pre-filter can reduce organics and thus carbon. Skimmers are effective tools, but need to be maintained frequently. Understanding the needs of cyanobacteria goes a long way in the battle of unwanted Blue-green algae. It does not mean that the hobbyists will necessarily win this particular battle once it has begun, but if the hobbyists could prevent the battle to begin with then he or she has accomplished a major victory in the battlegrounds of their biotope.

         Cyanobacteria growing on the Biocenosis baskets inside the Anoxic filter.

However it will not last long and if I had my druthers, which I do, I would choose my cyanobacteria to be in my filter and not my pond.

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