Hydroponics experiments - Daves

Hydroponics
System Design

Here is a basic hydroponics system design that I have tried and tested over several seasons and have made for several friends. It is a bit more complex than the simple starter system described in my Diary, but it has the advantage that you can run it as an NFT system, or as a flood and drain (ebb & flow). Both types of system have their pro's and con's. I primarily use it in the flood and drain mode.

Hydroponics System design

The design works on the recirculating principal but with a bit of modification, I suppose (i've never done it) you could use it as a run to waste system.

Anyway it works as follows. Water is pumped from a reservoir to one end of a plastic tube were it travels through the plant roots and completely covers them. It then gradualy drains and returns by gravity to the tank. As an NFT set up the water is pumped continuously and is not so deap (3 - 4mm).

In flood and drain mode the pump cycles on every 30 minutes for 15 minutes. This timing must be varied depending on the air temperature and subsequent water demand of your plants, the warmer it is the more frequently you will need to run the pump. This diagram should help explain the two modes.

The plants grown will need to be past the seedling stage with enough roots to reach the nutrient, I generally grow the seedlings in soil then wash it off and put them in the system, a purest might try rearing them in rock wool but that gave me less reliable results..

To exactly copy the design you will need

  • Main tubes - 6 x 1 metre lengths of 90mm UPVC pipe
    12 x 90mm end caps
    6 x 13mm rubber washers / grommets.
    30 x hydroponics type net pots to grow plants in
    A small quantity of expanded clay beads.

  • Feed tube - 3 metre's of 13mm black polythene pipe
    1 x 13mm tap/valve
    1 x 13mm T piece
    2 x 13mm end stoppers
    Short length of 4mm black polythene tube (1 meter should be heaps)
    6 x 4mm taps

  • Drain tube - 2 x 1 metre lengths of 40mm UPVC pipe
    2 x 40,, end caps
    1 x 40mm T piece

  • 1 x small pond pump, preferably with an in built filter.
  • 1 x rubbish bin at least 50 liters capacity to act as the nutrient holding tank
  • An electric plug in timer is also useful to cycle the pump on and off.

The system consists of six 90mm diameter Main tubes, these will have a cap on each end and 5 holes cut into each for the net pots (commonly available at hydroponic suppliers), a hole is drilled on the underside at one end of the main tube, with a rubber grommet fitted to hold a short length of 13mm Polly pipe for the drain spigot.

Main Tube - Hydroponics

There will be a cross pipe acting as a Drain tube, this can be of a smaller diameter than the main tubes, I used some 40mm pipe I had in my stock. The cross pipe will have six 13mm holes drilled in to it, with a T piece in the middle for the return of the nutrient to the tank and caps on each end.

Drain Tube - Hydroponics

You will need a small pond pump, this doesn't need to be large but it must have the capacity to lift water 1 metre high (known as the head). The pumps flow rate isn�t terribly important as if it�s too much you can add in a simple pressure reduction system using two taps and a T piece, most small pond pumps don't seem to worry about having restricted flow.

The Feed tube takes the water from the pump and delivers it to the main tubes, to do this you will need to create a manifold to distribute the water between the 6 main tubes. I have used 13mm polythene tube which takes the water from the pump to a T Piece then continues in 13mm pipe, with six 4mm taps leading off and into the main tubes via 4mm tube. I use the 4mm taps so that you can shut off each of the main tubes if they are not in use, but you could omit them if you like.

Feed Tube - Hydroponics

If space doesn't allow you don't have to have as many main tubes and they can be longer than I have used here, or shorter but I think shorter would be inefficient. You can expand the system latter by adding more main tubes. 100mm pipe for the main tubes is best if it�s available and flat bottom hydroponics channels would probably be even better but that is expensive. I've used 90mm pipe as it's cheap and very available here in Western Australia. Anything less than 90mm diameter would be too small, 90mm is only just big enough really.

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You will need a supporting frame work of some sort, I used four steel star pickets hammered into the ground with two bits of timber between each pair attached with wire, you could use two saw horse or something similar. I use nails knocked in to the timber to stop the main tubes rolling around but be more inventive and elaborate if you like.

I bury the main tank into the ground so that the top 100mm sticks out of the ground. This is better as it regulates the nutrient temperature a little and reduces the overall height of the system. Otherwise you will need a ladder to get to the tops of your tomato plants, but I suppose not really a problem if your just growing lettuce or something.

I think you will be able to work out how to assemble the system from the diagrams and list of parts, the point being that this is a flexible design were you use what is available localy.

Nutrient

None of this is any good without nutrient, I use a commercial product and follow the instructions to the letter. Friends have tried Miracle Grow with added trace elements, but there seems little point to me.

Adjusting the nutrient concentration and the pH of the water is an essential to success in any hydroponics system. I would say that any of the nutrients available from the suppliers you see in the advertising on my pages will be fine. Some are clearly specific to the type of crop your growing though.

If you have any questions please feel free to email me.

 

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