Preface

Here I discuss setting up a small hydroponic system. Aquaponics systems are technically extremely demanding and are also subject to animal protection, which is why I would like to recommend that the reader do a study that reports on it under scientific criteria before setting up their own system . Of course, you can also get advice from us.

Building your own facility for home use or even just having your own miniature farm is a costly business. If you add up all the expenses and set your own hourly wage to zero euros, you quickly end up with 200 to 300 euros in one-off¹ material costs for construction and around 50 to 100 euros for fertilizer, water and electricity - per harvest. Anyone who has ever shopped in a wholesale market will grab their head and go shopping.

¹ ) There is wear at least on the pump. If you want to drive your dealer crazy, pay close attention to the receipt and simply exchange it if it is defective, as it rarely survives two years of continuous use. This means: ensure you have a replacement pump before putting the system into operation!

If you have a garden or backyard at your disposal and can count on sun and don't just want to give your extra side table a productive second life, you will get your money's worth with a little more effort and a bit of technical skill, even if not in monetary terms - as has already been the case mentioned, depending on the size of the facility.

The perfect place for hydroponics, at least in cooler latitudes (with frost), is the greenhouse. In this article we will design the system outside  the home , but without a greenhouse. So an outdoor hydroponic system. This can be operated for six to eight months, depending on the weather.

Design and sizing

For starters and this article I chose NFT (Nutrient Film Technic). This has many advantages but the disadvantages must also be mentioned:  A particular catch is the loss of all plants in the event of a defective pump or power failure.

Here you will find an overview of other system types...

Short version of NFT technology:

Per:

• low nutrient consumption
• low water consumption
• very high yield

Cons:

• High acquisition costs
• Power supply required
• Control effort required
• in the event of a power or pump failure: crop loss

The implementation of the system is very simple and requires relatively little effort. We first need a few meters of KG pipes  ( sewer base pipes ) to outline the design options. The use of sewer base pipes has many advantages. They are resistant to acids and alkalis and are very cheap due to their distribution. Starting at around €5 per meter and around three euros per angle, you can get by with just under 100 euros for a 20 meter system with a capacity of around 50 to 60 plants. By the way, these pipes are not frost-proof - whatever you want to plant in winter, please write to me!

Installation location

The available KG pipe types (bend, pitch, etc., see photo below) allow great freedom in designing your own system. The only point that you should always keep in mind is the necessary gradient that an NFT-type investment requires. In combination with the rise performance of the selected pump (see table below), the maximum gradient on the pipe section is also determined. So from the point at which the nutrient (water with fertilizer) is pumped into the system to the drainage basin, the height difference may only be as high as the maximum delivery head of the selected pump.

With the aquarium pump we used, it reached its performance limit at around 1.3 meters. In our system we have also added a reservoir of 65 liters. The 20 meter pipe we use for this has a gradient of around 1.2 meters  over a 20 meter length. Less gradient quickly reduces the oxygen content in the nutrient solution.

The blueprint

It is advisable to make a sketch before cutting the pipes to size (if necessary) and putting them together. Putting it together requires some physical effort or you can smear some cooking oil on the rubber seal. Dismantling the pipes if you make a mistake or want to rebuild them is very laborious. 

This sketch serves as a guide to estimate the dimensions of the system. A pipe element is one meter long. A 90 degree bend takes up about 25 x 25 cm of space. The large blue barrel serves as a reservoir. From this, the nutrient solution is pumped into the pipe system using a pump. After the nutrient liquid has left the pipe system, it is collected in a flat bowl and pumped back into the reservoir. The pump that empties the bowl runs slightly faster than the reservoir pump (above). The purpose of this constellation is to always have enough reserves in the large bins. Since the plants (approx. 30 tomato plants) in this system can use up to 30 liters of water per day (in Portugal at 40 degrees Celsius in the shade), and we only want to refill the system once a day. In addition, the low pump performance (1.3 meter rising height). Now the nutrient has to be taken from as deep a place as possible, but only pumped up 1.3 meters. Therefore, this system configuration cannot be implemented with just one large reservoir. That would be it, only with a barrel height of one meter and a pipe gradient of around 1.2 meters, the feed pipe would be at a height of 2.2 meters. Nobody wants to climb there to harvest the plants.

What's lost in this sketch is the third dimension.

Plant

You can find a list of suitable plants here. 

Energy requirements

Now we come to the aquarium pump, which circulates the nutrient solution.

A quick note about aquarium pumps for home systems: In view of the customer comments, the technical data that is available can be viewed as more than speculative, not to say highly doubtful. Comparison portals, of which there are a surprising number, seem to use customer ratings rather than technical measurements as a criterion. Anyone who has anything to do with technology or science will probably have their hair standing on end.

All information in this list is based on manufacturer information and should always be viewed with doubt.

*) The Evenes model is only mentioned here as an example to show a comparison between a highly optimized circulation pump and aquarium pumps. Such a  circulation pump costs between €100 and €200. The usual lifespan is around 15 years of operation - ask your plumber for a good quote. The aquarium pumps are available from €20. For long-term operation, you should not underestimate the electricity costs.

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