Original prototype bell siphon
There are two types of aquaponic growbeds:

• floating raft (plants floating with their roots in a constant stream of water)
• media-based growbeds (plants growing in some sort of rock/sand/gravel/beads)

Media-based systems are recommended for home hydroponicists because they are simpler and more reliable. Media-based systems are also referred to as flood and drain. The idea is you flood the growbed with the fish water (delivering nutrients and, um, water), then let it drain out (bathing the roots in air/oxygen).

Of the various ways to flood/drain a media-based growbed, the one that is easiest on the checkbook is a bell siphon. All a bell siphon needs are simple plumbing bits available at any hardware store. Oh, and a small pump. I loved the way the folks at EcoFilms explain it in their post about How an Aquaponics System Works:

"If the pump is the heart of an aquaponics system, then the auto-siphon are it’s lungs. A vital part of kit. Remember when you were a little kid and the teacher told you about the regular flooding of the Nile river and how fertile the Nile delta was to early farmers. Well think of the auto siphon as a kind of similar concept. It’s main purpose is to flood the grow bed drawing rich oxygen into the depths of the trough, oxygenating the plant roots and turbo charging the bacteria to do their thing."

Below is EcoFilms' animation of how a bell siphon works.
[The red button toggles the animation on and off.]

A real-life system takes many times longer to fill than the time to drain (my initial prototype system with a single growbed took 10 minutes to fill and 1 minute to drain, ignoring the dribbly parts at the beginning and end of the siphon). I found the growbed in my system only needs 10 gallons to fill the spaces between the rocks, so the change in the level of the water in the fish tank is only 2-3 inches, about 10%.

Basically, when water reaches the top of the siphon, water quickly drains out of the grow bed, sucking air down around the roots and oxygenating everything. You can have a small pump running continuously, rather than a big pump turning on for only a few minutes once an hour or so. Since the pump is on continuously, the water in the total system is also cycling continuously, which my fish and plants love.

I didn’t invent the bell siphon, but I have developed a design that doesn’t require solvents, a design that can be manufactured with just plumbing bits and a mitre saw.

I'll show the bell siphon working in tomorrow's post about the coanda discharge - for today the video just covers the parts and assembly of the bell siphon.

Installing Bulkheads

Exploded view of Bulkhead Components
You have to do something to let water drain from the grow beds.

If I wanted to just have a simple flood and drain system, I could pump water in the grow bed for a while, then let the water gush or dribble out a hole in the bottom.

But as soon as I want to control that water in any way, I need to install a bulkhead.

The bulkhead I use for the 365 Aquaponics System is constructed from inexpensive PVC pieces you can buy at any hardware store. I use ¾” PVC pipe and fittings. If using metric plumbing bits, the equivalent size is 19 mm.
For some inexplicable reason, plumbing bits in the US are designed with a rounded edge. So for the actual part that penetrates the tank, I use PVC bits designed for electrical conduit.

The male PVC coupling bit is screwed down through the thickness of the tank. Once the coupling is tight, PVC will seat itself against the plastic tank wall in a nearly water-tight fashion. Slip a #18 O-ring around the male threads, then thread the female fitting as tight as you can by hand. The O-ring will make this bulkhead water tight, given that none of these bulkheads needs to withstand more than a foot or 300mm of water pressure.

Credit for this bulkhead concept goes to Richard Kinch, who details this bulkhead design at "An Improvised PVC Bulkhead Fitting for Liquid Storage Tanks."

Here’s a short video clip showing installation of a bulkhead.

Setting Up Tanks

Tanks and materials for the 365 Aquaponics System The first thing you need to have in an aquaponics system is a way to hold water. In order to achieve system stability and grow an interesting quantity of food and fish, you’ll want to shoot for a water volume of 250 gallons. That’s a lot of water. There are a lot of options. Concrete ponds, International Bulk Container (IBC) totes, 55-gallon drums, wood structures lined with plastic. For the 365 Aquaponics system, I chose stock tanks. Here are my reasons for using stock tanks. They are an existing and proven product. Stock tanks were designed to hold water for cattle, sheep, and other large livestock. They were designed to withstand day to day abuse from such livestock and the elements in which the livestock lives. Because plastic stock tanks are rugged, large capacity, and constructed from food grade plastic, they are often used by restaurants for food storage and preparation. Perhaps most important, they should be locally available. When you’re buying something this big and having it delivered to your home, you’ll pay a hundred dollars or more just for shipping. If you can get it in stock from a local agriculture store, the shipping to the store has already been covered by the store as part of the cost of doing business. They require little modification, if any. Grow beds in the 365 Aquaponics System have a single easy to drill hole (1” if using ‘English’ units, 25 mm if using metric). Beyond stacking some cinder blocks and planks, I don’t need to build support structures. So here’s a video clip showing me preparing the stock tanks for the 365 Aquaponics System.

365 Aquaponics

An early post at 3x5 Aquaponics
Just today I was reflecting that I need a new name for my blog.

I started this aquaponics blog almost a year ago. At the time, I wanted to prototype an indoor DIY system that would allow year-round gardening. I picked the name 3x5 Aquaponics because:

Anyone with a 3' by 5' area (that can literally support a ton of water/gravel/etc.) can have an aquaponics system for well under $1000. That's under $1000 complete with lights, fish, and rocks (most experts recommend home aquaponicists stick to rock-based systems).

I designed the system and created a prototype. Seeds sprouted, and I transplanted them to the garden.

It worked. But the taller my plants grew, the more I envied those who can grow outside. When my tilapia "failed to thrive," I was free to create a system outside.

The garden grew...

July 2011
And grew...

August 24th, after a month away
And grew.

After Hurricane Irene swept past, August 28th

I'm loving this aquaponics adventure. Alas, "3x5 Aquaponics" doesn't really describe what I'm doing now. What new name could I pick?

Then I browsed to the Aquaponics Association website, to review what the site is promising about what I'll present this month in Orlando...

...Meg Stout of "365" Aquaponics
365 Aquaponics.

Year-round gardening.

It's perfect to fit where I am now in my journey, as well as including my original idea of a small indoor system.

So thank you, thank you, thank you to whoever decided I was 'Meg Stout of 365 Aquaponics.'

I'll continue to cross-post here for the rest of 2011, but all future posts will go up at 365 Aquaponics first.