Wednesday, December 1News That Matters

How to Make a Homemade Aquaponics and Grow Lettuce in Your Backyard

Growing lettuce at home with aquaponics is a great alternative. Currently, the demands of modern life, as well as the consequent lack of time, often make it difficult to find fresh products in markets to place on our table.

Hence, more and more people are interested in growing their own food at home.

But how to do this, if we do not have land to grow our vegetables?

That is why it is a viable option to combine the cultivation of vegetables in hydroponics using water from fish farming as a nutrient medium; So this system known as aquaponics does not require large spaces and can be done at home in patios, garages, roofs, and even balconies.

Imagine, being able to grow your own lettuce, tomatoes, or cucumbers on your balcony!

Of course, starting an aquaponic culture at home requires a basic knowledge of the technique, for which we should document ourselves; however, once the system is established and balanced, the operation is simple and can be carried out by the members of the family themselves.

It just takes a little investment, imagination, and of course…. the desire to do so.

Advantages of aquaponics at home

  • The advantages of growing our vegetables at home using aquaponics are numerous, including:
  • Low cost and recyclable materials can be used.
  • It requires little space.
  • Design and construction are simple.
  • Obtaining food in a permanent and timely manner, suitable for family consumption.
  • Plants and animals are easily harvested.
  • No fungicides, pesticides, growth hormones, or antibiotics are used.
  • It can be operated by women, young people, or the elderly.

Why grow lettuce in aquaponics?

Lettuce is one of the vegetables most used in aquaponics, and it has certain qualities that make it suitable for growing at home; as they are:

  • Low nutrient requirements in cultivation.
  • It grows quickly, being able to consume its leaves in three weeks.
  • It adapts well to growing in hydroponics.
  • It does not require a lot of sunlight.
  • It has a short root system, so they can be grown close to each other.

What do we need to grow lettuce in aquaponics?

The elements necessary for an aquaponic culture vary depending on the system used and the dimensions of available space; but in general, the following materials and equipment are required:

Materials

  • Container for fish
  • Hydroponic bed
  • Lettuce seeds or seedlings
  • Fish fingerlings

Equipment

  • Air pump
  • Mechanical filter
  • Biofilter
  • Water Pump
  • Water supply lines

Container for fish

Practically any container can be used at home to keep our fish, from a fish tank, bathtub, to a tank; in fact, they can be made of different materials such as plastic, glass, or metal and have variable shapes and sizes. In the Philippines, a plastic barrel is recommended.

In the same way, we must remember that the volume of the tank will depend on the amount of fish to house; and this, in turn, will depend on the number of plants we want to grow, which we will review later.

Hydroponic beds

Lettuce, like other green leafy vegetables, can be grown in three different types of hydroponic systems:

  • Floating root system.
  • Medium beds
  • NFT system

In such a way that the choice of each one will depend on the budget that is available and the space available.

Selection of lettuce seedlings

Normally the transplants in your aquaponic installation are carried out with the plants already germinated and grown as seedlings that can be bought in nurseries; You can also plan the sowing and germination in seedbeds yourself.

It is important to choose healthy seedlings, of good size and with 2-3 leaves to be transplanted to the hydroponic system.

Air pump

It is necessary to supply oxygen to the fish to avoid mortality; but in addition, a decrease in oxygen can lead to a decrease in pH, which can cause stress in plants.

Also, depending on the size of the fish container, it can be an aquarium aerator or a small aeration pump in tanks of approximately 1,000 liters of water; with at least two air injection lines in the tank and one in the biofilter.

Mechanical filter

The function of this filter is to remove heavy solid waste such as feces and food remains, coming from the fish tank; in order to prevent them from reaching the roots of the plants, where they can cause suffocation of the roots.

For this purpose, it is located after the fish tank or tank and can be made using a 200 L drum; to then layer different filter materials such as:

  • Sponges of different pore sizes
  • Porous stones
  • Activated carbon

Biofilter

After the mechanical filter, the biological filter or biofilter is placed, whose function is to house the bacteria responsible for the conversion of harmful ammonia; especially the one coming from the fish tank in nutritious nitrates for the plants.

To make a homemade biofilter you can use a plastic container with a capacity of 20-25 L, in which low-cost materials are placed such as:

  • Polypropylene plastic caps
  • Pieces of a corrugated hose
  • Pieces of pottery, etc

Water Pump

This is practically the heart of the system since it keeps the water circulating from the biofilter to the plants; so it can be a submersible pump that is placed inside the biofilter, or in a subsequent tank known as a sump.

Water supply lines

These are smaller PVC pipes that water travels through, from fish tanks to plants; and vice versa.

Equipment to monitor water quality

Regardless of the size of your aquaponic system, it is vital to monitor pH, oxygen, temperature, and nitrates at least once a week; so measurement kits or equipment are required that can be easily found in aquarium stores.

What should we check before starting the crop?

Choose the site

The site chosen for the installation of the aquaponic system should take into consideration the following:

  • Have enough space for growing fish and plants.
  • Have good lighting for at least 6 hours; if the system is placed indoors it can be achieved with white light lamps.
  • Protection against rain, wind, or frost; if it is carried out outside, the construction of a greenhouse may be required.
  • Locate a nearby electrical outlet for pumping, aeration, etc. equipment.
  • Secure a nearby water intake and drain.

It should be noted that if drinking water is used, it must be aired at least 48 hours before introducing it into your aquaponic installation; to remove its chlorine content.

Choose what type of system to use

In the case of hydroponic lettuce, the most common is the NFT system; For this, tubes or gutters with lids are used through which a thin film of water from the fish tank is made to run.

Said pipes have holes where the plants are placed in containers with the substrate, leaving their roots suspended, which are put in contact with the film of the circulating solution; later, the water is collected in a reservoir or returned to the fish tank.

It should be noted that one of the benefits of this system is that the pipes can be arranged in many patterns to make better use of space; You can also make use of vertical space, walls, fences, or balconies.

Also, the construction of this system can be done with materials found in the home, or with commercial products with specifications and design.

In this sense, as a reference, the designs proposed by FAO for a family aquaponic unit on a 6 m2 surface can be used, using a 1000 L tank; for an estimated annual production of 20 kg of fish and 150 kg of vegetables.

Choose the species of fish

In some home aquaponics systems, plant culture is the highest priority, and fish are often not consumed; That is why they are used as a natural source of nutrients for plants or as ornamentation.

However, if you want to use a fish for consumption, a good candidate for the tropics is tilapia (Oreochromis sp.); In fact, it is the most used in aquaponic systems with lettuce, since it has qualities such as:

  • Rapid growth rate.
  • Adaptability to high population densities and resistance.
  • It accepts a wide range of temperatures between 20 and 30 ºC.

However, if you want to use ornamental fish, some options are:

  • Goldfish (Carassius auratus).
  • Guppy (Poecilia reticulata).
  • Swordfish “aquarium” (Xiphorus helleri).
  • Scalars (Pterophyllum scalare).
  • Mollys (Poecilia).

Define the number of fish and plants

The fish and plants in the aquaponic system have to be in an optimal proportion since if there are few fish, few nutrients are generated for the plants; On the contrary, if there are much fish the capacity of the biofilter to transform ammonia into nutrients that can be used by plants is reduced.

Ideally, start with a few fish, a recommended ratio is 1: 2, that is, one fish for every two plants.

For example, a family-level aquaponics system should start with a small facility with few fish; in order to learn the basic management of aquaponics and then expand it if you want to produce more fish and more plants.

Fish size

An adequate weight of fish to start aquaponic culture is 25 to 50 grams since small fish require more food (in the percentage of biomass) than large ones; so there will be a good proportion of nutrients in the water that will be used by the plants.

Similarly, when the fish grow, the total biomass will increase and more food will be added to the fish, so the growing area of ​​the plants can be increased.

Calculate the volume of water in tanks

Once the number of fish is established, the volume of water in the tank to be used can be better defined.

A recommended density is 500 grams of fish per 50 liters of water; that is, if you have 10 fish with an average weight of 50 grams, you will need a container with a capacity for about 50 liters of water.

But be careful to start with a low density of fish to start; and when the handling is controlled gradually increase the number of fish.

Putting the system into operation

Installation of bacteria in the system

Once you have the fish container with water, but no fish and the hydroponic system installed, but no plants; then the submersible pump must be turned on and kept in operation for 4-6 weeks so that the bacteria colonize your entire installation.

In such a way that these bacteria will be responsible for converting the nitrites produced by the fish into usable nitrates for the plants.

To speed up the process, the fish feed can be added to the fish tank (without fish) to act as a substrate for nitrification.

Introduce the fish first

After a few weeks with the pump running, it is time to introduce the fish.

The fish we buy come in bags with different water than our tank, so they must be acclimatized beforehand; For this, the bag where the fish come from is placed, unopened, inside the tank and left like that for 30-45 minutes to equalize the temperatures.

Then, add a little water from the tank inside the bag, wait 15 minutes, and repeat this operation up to 3 times; finally, the fish are released into the tank.

Introduce the plants

Lettuce seedlings are carefully transplanted into leaky containers with a certain type of substrate that will support the roots.

Afterward, these containers with the seedlings are placed in the holes of the channels of the NFT system; and thus leave the suspended roots in contact with the water coming from the fish.

System maintenance

  • Feed your fish
  • Fish should be fed a quality diet daily, preferably balanced or flake feed.

It is also advisable to offer food to the fish two or three times a day, noting that there is no food left in the tank after five minutes; to avoid overfeeding.

It has already been indicated that the amount of food depends on the cultivation surface of the plants, but a guideline may be to give about 15 grams of food daily for about 10 fish of 50 g each; therefore this is equivalent to feeding them with 3% of the total biomass, which is recommended for growing fish.

Maintain pH levels

Lettuces require a pH of around 6.5 – 7.0 for the proper development of the plant; however, in aquaponics, the pH tends to drop due to the action of bacteria and the metabolism of the fish.

So, it is important to measure the pH of the water with some frequency, at least once a week; For which there are very simple tests to use and that are available in many stores related to the maintenance of swimming pools or aquariums.

For example, to raise the pH, small amounts (3 g / 100 L) of calcium hydroxide or potassium bicarbonate diluted in water are added to the tank; and thus obtain the desired pH value.

Measurement of temperature, oxygen, and nitrates

Other parameters that must be measured with some frequency in the fish tank are:

  • Temperature: measure once a week, keep between 18 and 30 ° C.
  • Oxygen: maintain 5-6 milligrams of oxygen per liter of water or 5-6 ppm (parts per million), through aeration.
  • Nitrates: measure every 15 days, maintain an interval between 40 and 80-100 ppm making water changes to reach high levels.

Aquarium shops have tests with which these three parameters can easily be measured.

Other routine operations for your aquaponic facility

  • Replenish the water level in the tanks due to evaporation and evapotranspiration losses.
  • Eliminate the remains of solids that are deposited at the bottom of the tank or filters.
  • Clean biofilters (if you have them).
  • Check the flow rates to verify that the water is flowing well between the tank and the hydroponic culture.
  • Check your plants for signs of deficiencies or disease.

As you may have seen, growing lettuce at home using aquaponics requires some initial design and construction work; but once installed, it only takes a little time to care.

And best of all, you can harvest your lettuces when you really need them, being a healthy and sustainable option for your family.

See Also:

Leave a comment

Leave a Reply

Your email address will not be published. Required fields are marked *