What the heck is this green stuff?
Anyone who has experience with aquariums or ponds has spent some time dealing with various types of algae. From green diatoms to the dreaded black beard algae, these photosynthetic powerhouses come in many diverse varieties. Some algae, such as diatoms can live as free floating cells in the water column. These types of algae can cloud the water and tint it a green color. Other types, like hair algae form large colonies of cells that look something like plants to the naked eye. These primarily survive anchored to surfaces. Color can tell you a lot about what kind of light requirements a given algae might need. As a rule, green algae need bright full light to thrive. Brown algae are capable of thriving under lower light conditions such as might exist several feet or in a dimly lit tank. Red algae are tolerant to low light conditions as might be encountered around the openings of caves or in the shade of other algae/plants. These are general terms. Some green algae might look quite yellow, some brown algae might look fairly green and so on.
There is another organism, often mistaken for algae, that many aquarium and pond owners grapple with: Cyanobacteria.
Many reef hobbyists are familiar with red cyano but a lot of folks don’t realize that this photosynthetic fossil comes in shades of green and can also plague the freshwater aquarist!
As I mentioned, cyanobacteria is not algae at all but it is photosynthetic. This means that it uses energy from the sun to convert carbon dioxide into sugars and release oxygen, just like plants and algae. In fact, many scientists believe that cyanobacteria were among the very first organisms to perform this trick in earth’s history! They were so good at it that imitators were sure to follow but cyanobacteria have continued to thrive ever since.
Green cyano, like its red cousins tends to appear sort of slimy and/or blobby. Unlike algae which are capable of anchoring tenaciously to surfaces, cyano is easily blown away by a simple wave of the hand nearby. Don’t bother using algae treatment chemicals on cyanobacteria. Instead, is you want to use chemicals for control of cyanobacteria you’ll need to seek out specific treatments.
Luckily for us, cyano is just like algae and plants in terms of what it needs to survive: nutrients, carbon dioxide and light.
The best way to control algae or cyanobacteria in ponds and aquariums is to prevent it from gaining a foothold by controlling the input of nutrients, light and even carbon dioxide to starve the them out. This can mean limiting the amount of food we feed our fish, shading all or part of a pond, fostering plant growth to out-compete pests as well as other strategies.
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