This is the Goldfish Tower. At least is will be once I add the goldfish. Right now I’m letting it cycle before I add fish.
The Goldfish Tower started life as an EZgro hydroponics unit. I bought it a couple years ago as an experiment. Frankly, I didn’t like the results. I don’t believe, though, the poor results were because of the unit. It was user error. I didn’t keep the nutrients in balance.  Heck, I think I let the tank go completely dry a couple of times.
I pretty much lost interest in hydroponics because of the lack of sustainability. The nutrients could not be acquired or made locally and certainly don’t exist in nature. Hydroponics just didn’t fit our model.
Shortly after abandoning the EZgro to the garage, I learned about aquaponics and suddenly what I considered an obvious flaw in the hydroponics concept was overcome. Fish are sustainable. The fish food can be grown in the garden and the fish create the plant nutrients, so the EZgro was back on the team.
The unit is quite simple. At the base is a 5 gallon tank. In the bottom of the tank is a small water pump. A section of pvc is connected to the pump and functions both as center pole to hold the grow beds and a conduit to carry the water. Each of the grow beds has four growing chambers for plants. The grow beds are filled with media. The original system used a mixture of vermiculite and perlite. I have chosen to use hydroton, which is expanded clay pebbles. They are light weight and hold moisture and bacteria well.
Water is pumped up through the pvc conduit and into the top chamber. The water (carrying nutrients of course) trickles down through each layer and back into the tank below. The plants get the nutrients from the water and the hydroton acts as a bio filter cleaning the water then returning it to the fish.
I added an aquarium heater to maintain a comfort zone for the fish and an air stone to keep the water aerated. The pump, air stone and heater all use electricity and as such, compromise the sustainability model. Once I figure a way to use solar power to generate the electricity we remove most of the compromise.
The concept is sound, but the system as implemented has some weaknesses. First, the tank is small. I can only keep a few goldfish even with the addition of the air stone. I’m going to try for 10, but believe that could upset the balance in the system. Five would be better, but I’m not convinced that 5 one inch goldfish can generate enough nutrients for the number of growing chambers in the unit.
Secondly, I have questions about the water pump. I think it’s too weak. It is not a true flood and drain as it doesn’t actually flood anything. It trickles. I could probably use a different pump and will consider that if results demand it.
The weakness of the pump leads to a third potential weakness, which is the hydroton. I like the pebbles for flood and drain, but I’m thinking the slow, trickling water flow may require a growing media that has some wicking capability in order to hold moisture. Perhaps a layer of coconut coir on top of the hydroton will fix the problem.
We won’t know anything until we try. I’m quite prepared to make modifications as we go. I am going to plant spinach and butter crunch lettuce as my first crop. Stay tuned for updates.
I see. So, are you using this as a test model to build your own system later on? Hydroponics is a facilitating subject, like having a miniature pet ecosystem.
Damon: Exactly, my friend. We are testing different methods on a small scale to see what works best for us. We are setting up our first small scale Tilapia system in the next couple of weeks. I’m very nervous, but I’ve had the parts for a while and now it’s time to build. This one will be a floating raft, continuous flow system. Historically, they use a bit more electricity, but also provide a higher yield in the grow beds.
I have seen several systems like this before and I love the idea, Do the plants live off the fish poo? Be sure to post back and let us know how it goes.