Aquaponic Methods

Three Main Methods of Aquaponics

There are potentially unlimited methods of setting up an aquaponic system.  But there are three main ones and those; I am going to focus on here.

Setting up any system, which works and aligns to all of Aquaponics main principals, will give you an Aquaponic System, so there is great scope for inventions here, but for most, this choice of three, should be quite adequate:

Flood and Drain

This method is the most commonly used form, mainly for non commercial or small-scale growers.  It is sometimes known as the ‘ebb and flow system’.

You have a pond or reservoir of water and 6-8” (20cm) deep trays of your growing medium, which can be something like aggregate type gravel or expanded clay pebbles, but there are many different things you can use.

Water is pumped up on a timer system for about 15 minutes, four times a day.  Flooding the grow trays, but not above the surface area of the growing medium, as this will rot the plants, unless you are growing semi aquatic plants such as Water Cress, in which case you would be advised to flood about 2 inches/5cm above the surface of your medium.

Water drains back into your water reservoir and the system is operational.

Some growers sow sees directly into the medium, but more success is usually achieved by germinating them in conventional seed trays first, washing off the compost from the young plants and then planting them in the medium.  The surface can often get a bit too dry for tiny seeds to get established and some tiny seeds, like Lettuce, will just get lost between the bits of medium.

Some growers actually stand pots of medium half buried in the medium of the grow tray.  This might be beneficial if the crop you are growing is prone to rotting, such as Courgettes, as it will lift them off the wettest area.  But for most stuff; I would dismiss such as an unnecessary extra cost.

Raft

This method is mainly used by big commercial growers.

Usually employing long flat bottomed grow trays, often the whole length of the poly tunnel or green house, with the reservoir of water and fish underneath.

In this system the lower parts of the plant’s roots sit continuously in the water.

Floating rafts of Styrofoam or floating board, cut to fit the trays; floats on the water, as it flows continuously through the system.

The plants are put in pots of medium and sat down in holes in the floating board, so that the lower part of the pot sits in the water.

For this set up; Coconut fibre is a good medium to use as it is buoyant and light weight.  Often growers use the kind of pots that are used for growing pond plants, as the roots have more exit points and crops seem to prefer this.   Whatever pots you use; they must be plastic and/or light weight and buoyant, as otherwise they would sink and sit on the bottom of the tray, restricting both root growth and the flow of water around the whole grow tray.

This method allows the grower to lift up whole sections to inspect them also to remove or replace individual plants.

NFT

Nutrient Film Technique

Used by large and small scale (back garden) growers.

Basically something like plastic guttering us used and a thin trickle of water goes through it.  Plants in pots of light weight medium or blocks of rock-wool cubes are sat in the water and light is prevented from getting to the roots by something like horticultural plastic.