Aquaponics Small Farmer Design Manual
Aquaponics is the art and science of recycling water from a fish tank, through a bio/filter for solids removal and conversion of ammonia to nitrogen, and then having the water (without solids) flow into a float bed of plants to use up those nutrients and then sending the water back to the fish tank. If it is not recycling the water back to the fish tank, then it is NOT aquaponics. Aquaponics is recirculating and reusing the same water over and over.
Aquaponics with cinder/bio-filter beds are 100% recovery of all fish food nutrients. Systems that use a solids settling tank to separate the fish solids and dump them from the system, loose up to 40% of the nutrition. I do not teach such systems. I feel I paid for the fish food, and I want 100% recovery of all nutrition that is available. On top of that I will add worm tea or compost tea to give the system all the trace elements and micro nutrients possible.
This manual is to serve as an introduction to Aquaponic Farming using a Flood and Drain method of filtration. It is a simple method of with four elements.
1. The fish tank or pond. Anything from 50 gallons and larger. I personally think the 140 gallon tank is the smallest practical side.
2. The Bio-filter = You pump the water up to a bio-filter bed that is filled with material that would be a good bio-filter.......volcanic cinder, crushed gravel, river gravel, crushed glass, marbles, plastic beads, clay balls, or what ever medium you have available. I have seen hard bark chips used as a filter.
3. The Siphon = The fish water fills the bio-filter tray that is connected to a bucket siphon and at the peak point of this siphon device, such as a bell siphon or the overflow pipe device and once its started drains the water out of the bio-filter FASTER than the pump from the fish tank is pumping it in the cinder tank, then the water flushes to a deep trough grow bed
4. Deep trough bed = A deep trough bed is a container that has a foam float or plywood with holes to hold net pots. We focus on DEEP trough beds because deeper water is more stable and holds the temperature. Often called a float bed even when plywood trays are used instead of foam floats.
It is a simple system: the ammonia fish pooped water is pumped to the bio-filter that is home to the beneficial bacteria that turns the ammonia in the fish water to nitrite and then nitrate, a form of nitrogen that the plants can use for food. That clean water, now filled with nitrogen flushed down through the deep
trough grow bed and feeds the plants and then the water is pumped back to the fish tank.
Here is a sample system. We will start with a small fish tank, that started life as a horse trough, 140 gallons size. We will put only 120 gallons of water in the fish tank. We will install about 10 fish to start. Over the course of a month or so, we will add fish till we have 40 fish in the tank. We are introducing the fish slowly to allow mother nature time to supply the bacteria that will sense the ammonia fish water and deliver the bacteria to turn it into nitrogen for the plants. If you have a friend with an established fish tank, get some seasoned bio-filter medium or dirty water to inoculate your new system.
We will install a small submersible pump in the fish tank and pump water up to a BIO-Filter. That is a tray that is 6 to 18 inches deep and filled with bio-filter material, my favorite is with volcanic cinders, but gravel, small river rock or other available material will work.
The water will fill up to within one inch of breaking the surface of the cinder of bio-filter medium.
When the water in the bio-filter fills up, it is also filling up the siphon bucket at the same time. The bio-filter and bucket siphon are connect with a two inch PVC pipe, from the bottom of the bio-filter to the
bucket siphon. When the water fills the bio-filter, it also fills the bucket siphon. The siphon bucket has a overflow pipe that overflows when the water in the bio-filter is at maximum height, which should be about one inch below the surface of the cinder. When the siphon bucket overflows, it will start a siphon that will drain the water from the bio-filter four times faster than the water coming in. In practical terms, it means that if the pump takes 8 minutes to fill the bio-filter and siphon bucket, then it will drain out in 2 minutes or so. The rapid drain will move fine particles and sand though the system.
The siphon bucket flushes the bio-filter water down into the DEEP TROUGH beds, which are trays of water 6 to 12 inches deep and up to four foot wide and 120 foot long runs. But for our small backyard system we are going to use 20 gallon trays, 8 inches deep (same trays as the bio-filter).
The trays they we use are 20 gallon capacity and 2 x 3 feet and 8 inches deep. Being 2 x 3 feet, gives six square feet of growing room. That is room for 20 plants.
For the purposes of planning on how large to make your systems, you need the following information. You can have up to 1 fish for every 3 gallons of fish tank water, so in the 120 fish tank I can have up to 40 fish (120/3) . If I have 40 fish, then I will need one
gallon of BIO-FILTER for every gallon of fish tank water. If we have less than 40 fish I can get away will less bio-filter.
When we say one gallon of bio-filter tray for every gallon of fish tank , in our example, the 120 fish tank, (with 40 fish) will need 6 trays of cinder bed (bio-filter) to filter the fish waste. The math is 120 gallon of fish water, divided by 20 gallon size tray = 6 trays.
The next important formula for sizing the system is the question, How many DEEP TROUGH or float beds can we have. Well it is a simple formula, one square foot of Deep Trough for each gallon of fish tank water. So if we have 120 gallons of fish tank water, we can have 120 SQUARE FEET of Deep Trough tanks. That is the SURFACE of the tank cover. Since or deep trough trays are 2 x 3 feet (6 square feet) you divide 120 by 6 square feet and your answer is 20 trays. The holes can be drilled 20... 3 inch pots or 40... 2 pots. All depends on what you want to grow. I use only three inch pots and put anywhere from 15 to 30 holes in the lid.
How far to space the holes apart? Follow the spacing suggestions on the seed packet or garden books.
So now we have a140 gallon fish tank (horse trough) filled with 120 gallons of water, six cinder beds (bio-
filters) and 20 covered float or deep trough tanks. That is a garden 2 foot wide and 78 feet long ( 26x3 foot) and that equals a LOT of food. You will have 6 (2 x 3 feet) which is 36 square feet of bio filters for growing roots crops like onions, radish, taro, beets, carrots. Plus the 20 (2x3 feet=6 sq feet) deep trough beds for growing leafy greens, that is 120 square feet. Your total garden area is 156 square feet.
You can use the foam float in the 20 trays, or use the 1/4 plywood shelves with 2 7/8 holes, 20 per tray. With 20 plants in 20 trays, that is 400 plants in your garden. Plus the plants in the cinder beds (bio-filter). That is 20 plants times 6 trays is another 180 plants. So 480 plants at each plant rotation. Lets just plan for 400 plants for easy math.
SO... you have the capacity to raise 40 fish to maturity in 7 to 8 months, and harvest 400 plants every 3 to 4 weeks. For the year multiply 400 times 12 months, to see the potential harvest over the year, 4800 plants. At only $1 a plant (lettuce) or basil, that is $4800 a year. Grow a more valuable crop like cooking herbs and the profits can triple.
I have setup a back yard system with 1200 gallon fish tank (9 foot in diameter and 3 foot deep) holding 400 fish, and the water going through for 75 long deep trough trays (4 foot wide), and making a net profit of
$750 a week, just growing basil. This whole system fits in a very small back yard, 30 by 100 foot.
Did you notice above that it was suggested that you drill 2 and 7/8 inch hole for a 3 inch pot? Well that makes the pot stick up 1/8 inch.
If you are drilling for a inch pot, drill a hole 1/8 inch smaller. That way you pots do not fall through and they are easier to pick up an service.
In our drawing we show this sample system with just one cinder bed and one float bed. If you add more cinder beds, just connect their drains together and route it to the bottom of the bucket siphon. The one bucket siphon will drain all bio-filter beds at one time.
There are a few design principles to keep in mind. To flush the bio-filter, it takes 50% of the capacity of the bio-filter container. This a 20 gallon bio-filter, full of cinder or such, will need to have 10 gallons of water added to flood the bio-filter bed to the point that the siphon starts.
With this in mind, you never want to exceed the ratio of one gallon of bio-filter for each gallon of fish tank. That way you are leaving at least 50% of the fish water in the tank.
We once had a student connect 10 bio-filters (20 gallons capacity with 10 gallons of cinder in each) with the 120 gallon fish tank. By the time he filled the bio filter with 100 gallons of water needed to get the siphon to flush, the fish only had 20 gallons of water left to swim in! So never take more than half the water from the fish tank. So the 120 fish tank should not have more than 60 gallons removed at any time.
Now as you add deep trough grow beds, things get better for the fish. Each of the 20 gallon deep trough beds holds 15 to 20 gallons of water at all times. Add 10 of them to your system and the fish are now living in a system that has 120 gallon fish tank and 200 gallons of water in the float beds or a 320 gallon water world.
The more float beds you h