Derek Stobbard wrote me an email with this idea for nutrients:

“Here’s an idea for natural nutrients: Keep fresh water fish – goldfish, for instance. Once a week empty one fifth, to one third of the water from your fish tank and replace it with new water (preferably water that has sat in a bucket for a day – to get rid of the chlorine). Empty the water you took out of the fish tank into your watering reservoir. This water will be rich in nitrates from your fish’s “waste” which plants love, and if you feed your fish sustainable and organic food, so much the better. As long as you are doing this regularly, your fish water should not smell. Beware of algae, keep your fish tank out of direct sunlight, as algae will consume the nutrients and the oxygen from the water.

If you grow anything other than green leafy plants you may need to add very small amounts of calcium, iron and potassium from time to time (once a month). However, you may get away without it since you use clay pellets as a solid medium in your pots, and this has trace amounts of these necessary elements. Also, depending on the food you give your fish, some of these may already be present in the uneaten food, and will make their way into the water. ”

I love the idea and generally love the idea of aquaponics (fish + plant system). I continue to remain skeptical about incorporating fish into the windowfarm because forcing symbiosis between two different ecosystems is pretty complicated stuff and the balances can get out of wack really quickly meaning you could end up with a bunch of dead plants and fish really fast.

I like that he proposes simply using the fish water as a nutrient source and moving that water to the windowfarm after a simple filtration process. Anyone want to try it out? We would need a control group as well. Build two airlift systems- one using fish waste and the other using the recommended (Sugar Peak Organic Hydroponic Vegetative Nutrients) commercial nutrients? That would be rad, guys.

Remember everyone, creating nutrients is a pretty sophisticated biochemistry application so you gotta be ready to be super experimental. You probably will lose a lot of plants along the way. If you just want beautiful veggies you can eat asap, start by experimenting with existing hydroponic nutrients and only make slight modifications to start with.

Aquaponics is the method of growing plants hydroponically in combination with raising fish to supply nutrients to the crop.  There are two main components to this system, the grow bed and the fish tank. The grow bed uses various hydroponic systems such as water culture, ebb and flow (flood and drain), drip systems, or N.F.T. (Nutrient Film Technique).  The fish tank may be set up using edible fish like Tilapia or simply gold fish.  The waste created by the fish is pumped through the

hydroponic set up supplying the plants with their needed nutrients.  The plant is provided with water, oxygen, and mineral nutrients such as nitrogen, potassium, phosphorus, calcium, magnesium, and sulfur.
There are many reasons for growing plants using an aquaponics system versus a hydroponic set up or other conventional growing methods.  The main reason is to create sustainable food production.  Food can be grown locally, organically, and water is able to be re-used through bio-filtration and the use of a closed system.   A closed system is one in which the water and nutrient solution is reused instead being dumped after each use. Fertilizers are both expensive, energy intensive, and have the potential to do extensive environmental damage.  Growing organic crops hydroponically is not commonly done due to the high costs.
Fascinated with the idea of fish and plants growing harmoniously together I decided to set up an indoor aquaponics system in my living room.  The first step was preparing my 15gallon fish tank with an air stone and a goldfish, Professor Gillford.  He was to supervise and participate in the scientific process of growing spinach on top of his fish tank. The ammonia waste produced by my fish would be converted by bacteria into nitrite and then into nitrate.  The plant roots would then uptake the nutrients enabling the plant to grow.  I decided to create a deep-water culture for growing my crop.  It was the most logical setup.  I cut two squares out of one inch Styrofoam, cut one whole in the center of each square large enough to fit a hydroponic growing basket, then floated the little plant lifeboats on top of the water.  I purchased oasis cubes at the hydroponics store along with compressed clay balls.  In each of the growing baskets I placed a nutrient filled cube with a spinach seed and surrounded them with clay balls for root support.  Up popped the cotyledons of the spinach plant and away it grew.  As I went through the process of creating my small-scale aquaponics system I saw room for improvement.  I started to try to replace the growing products with recycled items.  For the grow baskets I saved yogurt cups and strawberry baskets.  I found that the yogurt cup was almost the exact size as the grow basket. I used a razor blade to vertically cut slats into the plastic to allow roots to grow out of.  The styrofoam had to go.  Even though I dumpster dived in the hydroponics trash for the foam I used, the idea upset me greatly. Little broken off bits were floating all around the fish tank.  I couldn’t help thinking of the already polluted ocean.  I decided to use a hot glue gun and secure wine bottle corks wrapped with silver wire onto the strawberry baskets.   Why should I use conventional ways on a totally unconventional system?  Wasn’t the point of aquaponics to create a more sustainable system?  I think so.  Using a water pump, plastic tubing and, recycled plastic bottles I began to set up a window garden.  Mr. Gillford would also supply the nutrients for the plants growing in my window.  Linking the plastic bottles together with fire and poking, on one side of each bottle I cut out the center. I then placed the grow basket inside.  The pump pushed water up through the plastic tubes and into the top of the plastic bottles.  The water then used gravitational pull to drip down through each pot and filtering back through into the fish tank.  So far was so good until I realized goldfish eat plants.  I put the goldfish in my water bowl outside and replaced him with five Mollies.  So the saying goes, “One inch of fish per gallon of water.”  My Mollies were all over an inch and are supposed to grow to two inches.  I added a strawberry plant and a sugar pea to the tank.  The pea plant is happily climbing up some copper wire and just produced its first pea.