What Kind Of Plant Food Do I Need For Aquaponics?

What Kind Of Plant Foods Do I Need For Aquaponics

While most people prefer traditional farming methods, some are venturing into hydroponics and aquaponics to cultivate plants and vegetables.

The kind of plant food you need for aquaponics include kelp powder, potassium bicarbonate, and chelated iron which all help to prevent deficiencies.

What is aquaponics?

Aquaponics is a farming system that combines aquaculture, or the farming of fish, prawns, and aquatic plants, with hydroponics, a farming method that cultivates plants in water. This system uses these two methods in a symbiotic way with fish excretion as the main nutrient for the plants. In exchange, the plants clean and filter the water that sustains the fish.

In addition to the fish and its excretion, the microbes have a vital role in plant nutrition. The bacteria converge in spaces between the plant roots, converting fish waste and solids into substances that plants need to grow.  This resilient farming system is a sustainable method that allows you to grow your own food and help conserve water as well. 

Pros and cons of aquaponics 

Aquaponics is a dynamic indoor farming method that provides better nutrition and wellness. Here we list some of its benefits and disadvantages of aquaponics.


  • plants grow faster 
  • reduced usage of water
  • conserves land, energy, and gas use 
  • vegetables are healthier and larger 
  • there’s no need to use artificial fertilizers 
  • it’s easy to set-up for year-round use 
  • there’s reduced damage from pests and disease 
  • no need for weeding and bending down on the ground 
  • you can have the option for fish meals


  • it’s expensive to set up 
  • you need to have a greenhouse 
  • it requires technical know-how’s 
  • you need to constantly monitor the water 
  • it requires electric energy output 
  • you can’t grow root crops 
  • it may be unsuccessful if one or more components may fail 

Do you needfertilizers for aquaponics?

Yes, you need fertilizers and supplemental nutrients for the plants to thrive.  This is because while fish food and excretion may contain the many of the required right nutrients this is not always the case in terms of quality or quantity.  While the important ingredients are nitrogen, phosphorus, potassium, calcium sulfur, and magnesium, the plants also need zinc, copper, iron, and manganese. 

These are the common deficiencies in plants of the aquaponics method:

  • iron –  you’ll know that there’s iron deficiency in your plants if there’s yellowing between the veins while the veins itself remain green. 
  • calcium – this mineral is part of the plant growth cycle and in its absence, the plant’s structure will disintegrate and water is not retained properly. With high humidity and little ventilation, the plants may struggle and still become calcium-deficient and tend to not lose water but also retaining very little of it. 
  • phosphorus –  plants that lack this mineral tend to have stunted growth especially during the early stages of its development. Look out for leaves that are reddish and have a purple hue. 
  • potassium – deficiency of this nutrient is characterized by brown scorching and curling of leaf tips, the appearance of purple spots on the undersides of leaves, and chlorosis or the yellowing between leaf veins. Reduction in the root, seed, and fruit development, as well as plant growth, are also observed among potassium-deficient plants. 

Nutrients and plant food for aquaponics 

These are some of the recommended plant food and nutrients that you need for your aquaponics farming method.

Kelp powder 

This fertilizer is soluble and easy to spray on plants. It’s beneficial to prevent pest attacks and helps to build stronger roots. 

Chelated Iron 

The chelates work as carrier to allow the iron to be absorbed by the roots of the plants and if chelates are not naturally released in plants, chelated iron is used as a supplement to combat iron deficiency. The best choice is Fe-DTPA as it’s effective so long as the pH is 7.5 or lower to sustain healthy plants. To add, aim for 2 mg per liter, calculate the size of the water tank and add the necessary amount at least every 3 to 4 weeks. 

Potassium Bicarbonate

It’s needed to balance the system, increase the pH, and promote the growth and flowering ability of plants and vegetables. You may use it by adding one teaspoon of potassium bicarbonate to a bucket of water, mix it well, and slowly add it to the aquaponic system.   

Calcium chloride 

It effectively treats calcium deficiency and can be applied by spraying it to the plants. Simply mix it with some water with a starting ratio of 4 teaspoons for every gallon of water and simply spray once a week. You may also add shellfish bones to the fish tank to increase the supply of calcium and phosphorus. 

Rock Phosphate

This is used to treat phosphorus deficiency in plants of the aquaponics method. The supplement may be added directly to the plants to allow the roots to absorb it instantly. Try to aim for 20 to 40 ppm for the plants. 

What are the factors that affect plant growth  and fish stress in aquaponics?

The factors that affect plant growth and fish stress in aquaponics include too high or too low temperature, incorrect pH levels, and electrical conductivity.  The erratic temperature may stress the fish and they’ll likely to eat less which could lead to disease and potential death and slow growth in plants. Incorrect pH levels also affect fish stress levels which may cause diseases while plants will struggle to absorb the needed nutrients and may result to slow growth. Bacteria are exterminated preventing the conversion of ammonia to nitrates which could pose great risks to the fish as high levels of ammonia can kill fish within hours. 


Aquaponics is a sustainable and feasible farming and environment-friendly gardening method. It conserves water, land, and energy use and allows families to have an attainable means of food production and good nutrition. However, plant food and nutrients like chelated iron and kelp powder are also needed to help it thrive.

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