Aquaponic Gardening: Phase II

Goldfish and minnows get acquainted with the Buddha. Photo/Nicole Caldwell
We told you last week about our plans to create an aquaponic grow station at Better Farm in order to grow salad greens, tomatoes, and peppers year-round.

Marching orders from our aquaponic/hydroponic setup consultant, Marco Centola of Brooklyn Farms, included getting our hands on at least a 40-gallon fish tank with two corner filters, gravel, and air circulator, letting water sit in the tank for two days, then adding a bunch of feeder fish to get the nitrogen cycle started.

I hit the pet store the next day to assess our options and make a note of prices, then scoured Craigslist to find great deals. We scored a 70-gallon tank and stand from Craigslist for $180—about $100 less than the cost of a new, 40-gallon tank and stand at the local big-box pet store in Watertown. Next up was picking out filters:
We also grabbed a pH test kit with "pH Up" and "pH Down" control additives, a bunch of fish food, gravel, awesome Indian sculptures, and even a few bulbs that will allegedly grow plants:

Here's an excerpt from an e-mail Marco sent to me outlining the process:
The first thing you should do is to setup the aquarium:
  • Rinse the tank well
  • Rinse the gravel well, food strainer makes the job easier
  • Place a flexible airstone at the bottom with the air line coming out and cover it with gravel (this is still on our to-do list!)
  • Fill the tank with water and begin aerating and filtering the water.
  • After 24 hours you can introduce the first feeder fish or you can put a couple of raw dead shrimp into the tank to begin the nitrogen cycle. 
After four days, you can take the dead fish out and replace with feeder fish.  From here you need to check ammonia, nitrite, and nitrate levels once a week. Feeder fish are cheap and WILL die but the purpose of them is to see when they can survive for more than four days. It should take from four to eight weeks to establish a strong enough nitrogen cycle to get some nice fish in there.  When testing, you will see ammonia spike high at first then nitrite, and finally nitrate. 

Though nitrate is safer, it is still toxic in large quantities and regular water changes are a must.  when you change water in a fish tank you must make sure there is no chlorine or you will kill all the beneficial bacteria that has already colonized.  I usually let water sit out 24 hours, which allows the chlorine to evaporate.  You should also only change 20 percent of the water at a time.  Fish are sensitive to temp, pH, and any drastic change, so this should soften the blow.

Is he the best, or what?! We added the fish yesterday (the woman at the pet store warned us the water would get pretty cloudy once the fish went in, which she said was normal as the nitrogen cycle begins and levels out. "Don't do anything when that happens!" she told me, "after a few days the water will clear.") Now, we wait a few days to see how the little fish fare. So far they've made it 24 hours with no fatalities (thank goodness for Better Farm's well water? Or is the good luck of our statuary?).

For more great information about aquaponics, visit Backyard Aquaponics.

More about our aquaponics experiment:
Aquaponic Gardening: Phase I