Turning a Fish Tank into a DIY Aquaponics System

Off The Shelf Home Aquaponics System

From 2012-2016 students and I designed, built, and ran an aquaponics system at Jasper Place High School. The aquaponics system was great for a school but way too big and expensive for the average home. The whole project was a fantastic experience, but I’ve been thinking about how to scale its size and design for home use. The goal – to create an elegant, home aquaponics system from a standard fish tank and off the shelf parts for as little money as possible. Here’s are my five design criteria:

1. Simple

   A DIY home aquaponics system needs to be as simple as possible. The system that I built at the school has a few particular parts – mostly the bell siphon – that took weeks to get right.  A home aquaponics system should be straightforward and beautiful. I want something I’d like to show off as well as something functional.

2. Foolproof

   The last thing anyone needs is dead fish, dead plants, and a flood. Good design is redundant, safe, and reliable. The smart aquaponics builder will ask, “what happens if the power goes out? Will the system implode and make a mess, or will everything survive?”

3. Affordable 

   There’s plenty of pre-packaged aquaponics kits, but they’re often costly. A DIY approach should be affordable and repairable. Replacement parts should be easy to find and simple to use. For this reason, I’ve also decided to build the system with standard fish tanks – the kind you can track down on Kijiji, Craigslist, or Bunz for dirt cheap or free.

4. Modular and Customizable

   Everyone’s needs are different. A home aquaponics system design ought to be flexible enough to adapt.

5. Achievable

   What use are home aquaponics plans if they require a master artisan to execute? DIY home aquaponics systems ought to be simple enough for a novice to build but flexible enough to be taken to the next level.

The DIY Home Aquaponics System Design and Build

The Fish Tank

I inherited a 40-gallon fish tank along with some fish, so I decided to use it as my base. I left the tank unaltered but replaced the conventional water filter with the growing bed and medium. As the fish excrete waste into the water, a small pump will periodically cycle it through the grow bed.

Aquaponics Grow Bed/Filter

Designed to rest on top, the grow bed box replaces the existing filtration system. Bacteria in the grow box convert the toxic ammonia in fish waste into nitrate that the plants can access.

I happen to have a lot of 1×8 pine laying around from some of my other projects, so it was an obvious candidate for building the outside frame of the grow bed. For obvious reasons, a wooden grow requires lining with something waterproof. I went with a coroplast insert lined with some pond liner that I picked up in the seasonal section of the hardware store. I’m happy to say that the inner-liner and wooden-outer of the grow bed has held up exceptionally well.

Aquaponics Growing Medium

You can’t use soil in an aquaponics or hydroponics system without creating mud – you need something that drains well and has lots of surface area for ammonia digesting bacteria to grow. Gravel can work, but it’s heavy, so I opted for more expensive but highly effective expanded clay pellets. Expanded Clay pellets are the one item in the build that might be a little harder to track down. Most cities have at least one gardening or hydroponics shop that will carry it, but you can also buy clay pellets online.

Aquaponics Plumbing

There’s are a few different approaches when it comes to plumbing an aquaponics system. The key to any method is providing a healthy mixture of water, nutrients, and oxygen to the roots of the plants. Too much water and the plants drown – too little, and they’ll dry up. I’ve found that a good mixture involves flooding the grow bed for 15 minutes every hour. We can achieve this through bell or U-siphons that automatically cycles water through the beds at regular intervals, but they can be complicated to build and hard to “tune” to the right balance of water and oxygen. To keep things simple, I opted to plug a small submersible pump into a $10 timer set to turn on once an hour for 15 minutes – done. Simple.

Lighting The Aquaponics System

The use of supplemental lighting depends on the location of your system. Mine’s inconveniently tucked away in my basement, so natural light isn’t an option. I opted for two $30 T5 lights – while not as energy efficient as LEDs, they’re much more affordable and available.

Of course, the obvious solution would be to pull the system out of the basement and into some direct sunlight.

Maintenance and Growing Food

The system requires minimal upkeep outside of the daily feeding and care of the fish. I’m pleased that I went with a timer to regulate the cycling of water – the plants seem to love it, and I haven’t had to fiddle with complicated siphon systems.

Adding plants is simple. I picked up some basil from my local grocery store and divided it into small plugs. They took quickly and provided a hefty handful of fresh leaves at least once a week – definitely haven’t bought any basil since turning the system on. I think your best candidates and bang-for-your-buck are leafy herbs. They’re easy to grow in an aquaponic system and are typically super expensive at the grocery store.

Order Details Plans and Turn Your Fish Tank Into A DIY Aquaponics System

If you’re interested in knowing more about this build or would like detailed plans, please send me a message through my contact page.