Everything Cycles: From Circuits to Fish Food!

Your friendly "Trout in the Classroom" crew is working with the teachers & students at Northeast Elementary school to figure out how to reduce high ammonia levels in their aquarium.  Ammonia is toxic to fish, so we need to fix this.  Usually a couple of water changes solves everything, but this time the problem is unusually persistant.  

To figure out why the ammonia problem is persisting, we need to do a little detective work.  So this is a great opportunity to consider the important role of nitrogen in our food web and in our aquariums.  We know that fish waste is has a very high nitrogen content, in the form of ammonia (a compound that includes one nitrogren atom and 4 hydrogen atoms, NH4) , so we know how the ammonia got into the water.  But a healthy aquarium (or stream) should have very little ammonia, so where does it go, and what's gone wrong?  And... how can we explain this to the students in charge of the tank?  

The answer hit me like an electric shock when I saw this on the whiteboard in Ms. Werner's classroom.

Of course!  When any components of a circuit is missing or broken, and electrons can't complete the full cycle, the circuit doesn't work!  That's just like Nitrogen in our aquariums.  We add nitrogen to our aquariums in the form of FISH FOOD.  Our trout eat and create waste that we observe as ammonia (NH4).  Bacteria change the ammonia to nitrite (NO2) and nitrate (NO3).  All the while, nitrogen is moving through the NITROGEN CYCLE!  

In Northeast's trout aquarium, the nitrogen cycle isn't working quite right!  While we're investigating, you can check out our new lesson plan and slide show on Circuits and the Nitrogen Cycle.   (Click on the "for Teachers" tab, above, for complete info!)

Maybe you can think of a few more cycles you've observed, or create a poster of the Water Cycle for the NY DEC "We all Live in a Watershed" Poster Contest (see prior post)!