For the first three weeks, our aquarium went through the standard series of nitrogen compound crises that a new tank experiences before it is "cycled", as the fish tank enthusiasts say. During those three weeks, our tank water was crystal clear.
About one week ago, our nitrite levels fell abruptly to zero, indicating that our "biological filter" was now colonized by all of the bacteria needed to complete the nitrogen cycle. As soon as the nitrite levels fell, algae began to grow. The water in our tank is quite green.
I placed a drop of our tank water on a microscope slide and viewed the contents at 150X with an inexpensive microscope I obtained in the 1970s. There I found green U-shaped algae with pointy ends. After a bit of google image searching, I conclude that the species of algae is Selenastrum capricornutum, or Selenastrum gracile.
It's fun to identify the organisms in your home. I recommend it.
Other species I have identified in my home:
- Homo sapiens notsosapiensis
- Danio rerio (zebra danios)
- Palaemonetes kadakensis (ghost shrimp)