Hydroponic Aggregates

Aggregates are mediums used to grow plants in, these provide support for the plants and affect moisture retention  and aeration around the roots of the plants.  Jiffy-7 are the easiest for propagating seeds and Perlite is the best medium for propagating cuttings.

When using aggregates it can be advisable to elevate your pump from the bottom of the tank to avoid sucking in residue from the aggregate.

Gravel

GravelCoarse, washed, river gravel is a good growing medium.  Gravel does not absorb any moisture and will retain some moisture on the surface of the gravel.  Gravel sized between 3mm and 10mm is best.

Gravel can be mixed with river sand or Perlite to maintain a higher moisture level in the growth medium.

Ensure that the gravel is carefully washed before being introduced into your hydroponic system.

Jiffy-7

Jiffy-7

The Jiffy-7 Pellet is made from sphagnum peat from specially selected peat bogs. Lime and a special fertilizer with a low ammonium content are added to the peat in order to stimulate growth. The pellets have a pH of approximately 5.3 and are wrapped in a thin, degradable net.

Simply sit in water and the pellet expands upwards. A small indent is on the top of the pellet, place your seed here once the pellet has absorbed the water.

Perlite

PerlitePerlite is a natural occurring substrate formed from volcanic glass,  it is porous and inherently retains water within it’s structure.

Perlite is excellent for rooting cuttings and can be mixed with other aggregates to provide ideal medium for use in your homemade hydroponic system.

Rinse the Perlite in fresh water before introducing to your hydroponic system to remove residual dust.

Vermiculite

VermiculiteVermiculite is a natural occurring mineral that expands when heated in a process called exfoliation.

Exfoliated Vermiculite does not retain moisture and generally is mixed with Perlite to form a growing medium.

The Vermiculite in the mixture provides great drainage, while the Perlite will retain moisture and in combination provides a moist aerated environment for plants to grow in.

Rock Wool

Rock WoolRock wool is manufactured by heating rock to 1600ºc and then either spinning it into fine fibres or blowing air through it resulting in fine fibres.  Rock wool is good at retaining moisture and can be used without needing to be contained in a pot.

Ensure that Rock Wool does not end up getting sucked into your pump or it will quickly block it.

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Nutrient Film Techinque (NFT)

NFT ChannelAs the name implies, the Nutrient Film Technique is a hydroponic system based on a moving film of nutrient solution.

This system is widely used in commercial hydroponic installations and can just as easily be used in your homemade hydroponic system.

A NFT hydroponic system can be as small as a single 1m channel to as big as you entire yard, give it a try and you will amazed at how well it works.

Basic Design

The basic components of a NFT system are a sloping trough or channel, a reservoir, a pump to circulate the nutrient solution and some plumbing.

Basic Operation

The nutrient solution enters the raised end of the sloping channel and flows in a thin film to the lower end of the channel where it flows into the reservoir.  The nutrient is recirculated to the top of the channel by means of a pump.

Image by chooyutshing via Flickr

Design Considerations

There are a few things to keep in mind when you design your NFT hydroponic system

  • The nutrient needs to flow not puddle around the roots of the plants to keep the roots from rooting
  • The nutrient needs to be kept in a dark reservoir to stop algae growing, you can paint the outside of the container to stop light getting in
  • The plants require air around the roots

Design Components

Channel

There is an almost endless number of items that you can use as a channel to grow your plants in, here are some of the ones I have used

  • Plastic roof guttering
  • Plastic down pipe with hole cut for the plants
  • A plastic film called Panda Film, this is black on the inside and white on the outside.  I lay the film on a board and fold the two edges up to form a triangular shape.

Reservoir

The size of the reservoir is dependent on the amount of channel that you are installing and the amount of plants you are planning to grow.  A small reservoir with a large number of plants will require dosing daily, a large tank with a large number of plants may only need dosing every two or three days.  Try and set up your channel so that as the nutrient drain from the channel they drop a distance causing bubbles in the nutrient solution, if this is not possible it may be necessary to use a fish tank air pump to aerate the nutrient solution.Reservoir for your Homemade Hydroponic System

Ensure your reservoir does not let light in and that it is not susceptible to corrosion.  Good reservoirs are made of plastic, glass or stainless steel, other materials are fine if you use a plastic liner.

Pump

Submersible Pump for your NFT System

There are a number of pumps that you can use, one of the easiest is a submersible pump.  The pump simply sits on the bottom of the tank with the pump intake on the side, a spigot is provided to attach some pipe to deliver the nutrient to the top of the channel.

Ensure you check the height that the pump is capable of pumping to, this needs to be more than the height of the high end of your channel.  This measure is generally known as the Head.

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