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Aquaponics 101

What is Aquaponics?

Aquaponics is a form of hydroponic gardening that uses fish waste as a source of natural fertilizer to grow plants. In this symbiotic relationship, the waste produced by the fish provides a food source for growing plants, and the plants naturally filter the water for the fish. This means that there is less maintenance required for the aquaponics grower, since the system is self-cleaning and does not require outside nutrients. Aquaponics is a great way to grow your own organic, pesticide-free kitchen herbs and leafy greens, which in turn will save you money on your grocery bill!

Here are some useful tips you will need to know in order to get started…

  • How Many Fish and What Kind?: You will generally need about 1lb of fish per 10 gallons of water, but this ratio can be changed by the amount of plants compared to fish in your aquarium. Any type of fish are suitable for aquaponic systems, but the most popular fish used are talapia, koi, perch, trout, and salmon.
  • Introduction to Cycling: Cycling a tank involves preparing the bacteria living in your aquarium to work in a symbiotic relationship with the fish and the plants. Here at SD Hydro, we like to get our system up and running, fill it with water, make any pH adjustments prior to adding fish and then we add the plants when the tank is stable. We let the system run like this, with no fish, for two weeks. During this time, the plants are starting to grow and they are creating the necessary bacteria your fish will need to survive. When the plants begin to yellow from lack of nutrition, you can apply a seaweed extract, such as Neptune’s Seaweed Plant Food, straight into the fish tank or as a foliar spray directly on the plant. After two weeks time your plants will be starving for nutrition and this is the ideal time to introduce your fish to the aquarium.
  • What do I Feed My Fish?: Feed fish high quality fish food pellets. The frequency in which you should feed your fish is dependent on the water temperature and is discussed more below. If you want a more sustainable feeding option, you can grow duckweed in your aquarium for the fish to eat.
  • What is the optimal pH Level?: The ideal pH for your system is between 6.2 – 7.2. Be sure to check the pH regularly and to adjust as is necessary. Try to only adjust your pH by .2 each day so you don’ t shock your fish. You can adjust the pH up with up with calcium or potassium carbonate. It is rare you will need to adjust the down as the nitrification process naturally lowers the pH.
  • What are the Ideal Water Conditions?: All fish have an ideal temperature range in which they can thrive. If the water temperature is too hot, or too cold, you fish will experience stress and could die. Most fish can live in a temperature between 50-85 Degrees Fahrenheit. During colder months, feeding should be cut down substantially and your fish should not be expected to breed. Large fish tanks may require the use of a tank heater, such as Sunlight Supply’s Aqua Heat, to maintain an ideal temperature. It is crucial to change out 20% of your aquarium’s water every week in order to maintain ideal bacteria levels.
  • Stress Factors: Cycling a system can sometimes take 8 months to a year to create ideal conditions. Don’t be discouraged if plants and fish are stressed at the beginning. There are many ways to stress your fish. Common stress factors include handling your fish, pH fluctuations and less than ideal temperatures.
  • What Plants Grow Best: The waste produced by the fish is high in Nitrogen, which is the most important nutrient plants need during their vegetative state of growth. Because of this, leafy greens, such as lettuce and kale, are the easiest plants to grow in an aquaponics system, since they are always in a state of vegetative growth. Most fruit bearing vegetables will also grow well (we grew bell peppers!). Root vegetables, such as onions and carrots, are extremely difficult to grow aquaponically, and we do not recommend trying to grow them.


For more in depth information on Aquaponics (such as the importance of the Nitrogen cycle and the role of beneficial bacterias) check out SD Hydro’s new book, The Indoor Gardening Guide, available at all five store locations for the low price of $12.99!

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